Tips needed for introductions

Does anyone have any good tips for introducing two pairs of rabbits? I now have four gorgeous house bunnies, Flapjacks and Fudge have been with me for a year and are 'healthy' sized dwarf lop and a dutch crossbreed. Recently I bought two baby netherland dwarfs, Coco and Honey. Although both pairs are bonded to each other I'm having trouble introducing the two pairs and I can't find much advice out there.

When I try letting them all out together in neutral territory the little bunnies get skittish and bolt around which scares the big bunnies and they grunt and try to bite. They all seem really interested in each other when they are separated by the pen gate. It would be great if they could all get on as the big bunnies have the roam of the flat so I hate having to shut them out of the lounge to give the little bunnies some exercise. Any ideas would be welcome!

Are they spayed/neutered?
Also how big of space are you trying to bond in?

I use a puppy pen for mine. I keep them inside it for 48-72hours.
With as little contact from me as possible. Just giving them food and hay and separating if needed.

x

The big bunnies have both been spayed and neutered but not the little ones yet. Coco is being neutered in the morning and Honey not till mid-December. Do you think when they are done the big bunnies will see them as less of a threat?

I was using a big puppy run to introduce the two pairs but Fudge isn't used to being confined in a cage and was getting really stressed so I ended up using the kitchen. Because of the size difference I am a bit worried about the big ones hurting the little ones.

Making sure your buns are neutered is a sensible first step. Also I came across problems due to the area i was bonding in it was too big! So you need a smallish space (maybe a bathroom) I think you need to expect a bit of argy bargy while they work out whos top dog but youll know when its getting into propper hand bags at dawn fight,if that happens,seperate them or you risk being unable to bond them at all
I must admit, it was difficult but worth it in the end