I also get very low on hay sometimes. It usually happens towards the end of a week, when ordering and delivering takes a bit longer too. Yes, my bunnies have had the soft timothy hay from timothyhay.co.uk. They ate very little of it, but then I know from experience that they just don't like soft hay. They even won't eat the soft hay we harvest from the garden. All bunnies are different in their preferences though, so it will be very interesting to see what your two think of it. As j&b said though, it's perfectly OK to feed just one type of hay. It's what I do most of the time. It just needs to be a hay that they will eat lots of.
Yes, I think it's fine to sprinkle the readigrass on the meadow hay. Regarding quantities, I think as long as you weigh them regularly, you will get to know how different quantities are affecting their weight. I would definitely opt for giving any sort of hay/readigrass in preference to pellets, as it has to be better for teeth and digestion. I think you'll get to a point when you've balanced it all perfectly, both are eating a lot of hay and their weight is remaining stable.
It's all sounding very positive
Thank you Omi for your reply. Yes it always happens on a Thursday or Friday and then the order is not necessarily processed before the weekend and sent on delivery. Hopefully my white board will help me remember.
Yes I realise it is trial and error finding a hay they will both eat lots of and one bun could love it and another doesn't touch it. Mischief has eaten enough of any hay we offer him to have a reasonably healthy diet. He loves anything edible to rabbits really! (He has also eaten things that are not supposed to be edible to rabbits though like my phone charger leads (too numerous to count), my pens, jotter pads, ruler, a candle, tablet case, cardis, bedclothes, the water pipe in the bathroom! In the 6 years we have had him that is, not as part of a balanced diet

Just to say that this paragraph is mainly for humourous effect and your things such as a charger lead should be kept safely away from your bun at all times. We try our best to but my bunnies are devilish creatures that pounce as soon as my back is turned.
Seriously though, we give them many more willow and other chew toys than before and now the fresh willow too!! And the apple twigs I bought from Binky Bunny! They had sold them all along and I have scrolled past them every month when I picked out what forage to order but I had only tried our two with the pear twigs from there. Not apple. Plus they have two chewable tunnels and they do chew them but not like they used to. A giant size willow tunnel used to last 2 days when it was just Mischief here. He didn't have his beautiful model bunny Lillabelle here then to keep him occupied

Now he has an even slimmer healthier model girlfriend. That makes me so happy. I think the Timothy hay has helped loads actually thinking about it....
Mischief's poops have always been big and fluffy but now they are huge with the new coarser timothy hay! Being as he is a big bunny as well they might seem massive to another bunny owner who only had teeny bunnies such as lionheads. Although teeny in size I am almost certain that they are massive in personality though. I have seen a video of a little lionhead running and leaping about with so much energy. My bunnies are very lazy in comparison but laid back is their nature being french lops. I say to my OH that I want some teeny bunnies. We have room as they could have the lounge I say. But really they couldn't as my grandchildren are in that room sometimes. Far too loud by far for a little lionhead's ears. And my OH also says no they would be too much excitement for us. And he would be right. I couldn't catch one to take to a vet appointment or whatever. They are far too quick for me and he is not much better with his hip osteoarthritis
Lillabelle is a fussier eater than Chief but she still absolutely loves her food. Her poops with the coarser timothy hay are bigger and fluffier although a black colour. With the Readigrass as well they are bigger and light in colour than that so I am glad you showed me that it is not much more in protein than other hay.
We have run out of timothy hay completely now. It shows already in their poop. Instead of being big and fluffy, Chief's poops have shrunk quite a lot already and instead of being light coloured they are almost black
Regarding the soft hay, I thought what if I am doing the wrong thing and they eat the soft hay instead of the lovely coarse timothy hay which is good for their teeth? Why order the soft hay at all? (OMG I've just realized that I can use my voice to write my posts on here now! I just have to say this because I'm excited. It is so much easier with Google voice as it takes me a long time to write a post now especially as they are usually long ones. I think the voice way needs tweaking as I am writing some bizarre sentences though

)
Back to the subject, the reason I am looking for a soft hay is because Lillabelle is still chucking the hay out of the litter trays and the timothy hay makes such a mess, especially as they are giant rabbits and need hay enough for them both in size daily. I thought I could just put a little of the soft hay at the end of the two litter trays just in the corners maybe? I will be careful to keep the amounts small but soft hay is easier to pile together and it stays in shape. By the way I forgot to mention, the reason Mischief was getting brown back feet is because Lillabelle was not only peeing on the tray near their hay but also pooping as well. ,
So I have been putting a sprinkle of Readigrass over their hay and it does encourage them to eat it even though it is just meadow hay. I did give Lillabelle half a bowl of it earlier before she's due her pellets and she did not even ask for her pellets. She is usually jumping up on the bed constantly an hour before they are due. She loved her half bowl of Readigrass. She ate all of it including the little amount on the floor which had spilled over. My OH gave her five pellets less to start with and we will see how her weight goes from there.
Chief was the one asking for his pellets. He had been lying next to the meadow hay but not eating it. I think he was waiting for his timothy hay

We saw this but thought if we hold out maybe he will eat more hay? But when we gave him his pellets he was ravenous. He nearly had my hand where he was eating so keenly. Not having the timothy hay is actually tipping the apple cart over as far as their diet is concerned. We are reliant on that to fill them up. I did offer him some Readigrass after his pellets as I was worried he could still be hungry. He ate a couple of mouthfuls out of the heavy china bowl I had hold of on the bed without conviction and he kept looking at me as if to say..but Mum! He then shoved the bowl away with both front feet violently and then tried to throw with his teeth! Perhaps not then. Mischief has always made it very clear when he likes or dislikes something by his actions
Yes I agree it is all going very well now and I'm excited to see how the Readigrass and the soft hay go as well. It is mad to think that only a few months ago these two bunnies were really obese and I was really worried about their health for the future.