Of course, although it wont improve tooth root issues
A bun can easily live on a hay only diet. They will eat it if forced to.
How many pellets is Spenser having, per day, roughly?
I've been through all this, as have many RU members. For health reasons, B&G only have 10 SS pellets per day - then just herbs and they eat so much hay its untrue.
We know Spenser is fussy - but i genuinely think (and this is no reflection on you or your care Susie) that you pander to him a little too much when he's being fussy. Spensers weight is stable - he's had his teeth checked and if the vet thinks thats controllable by diet, excellent. If not, and he needs burring etc, then so be it - thats fine too.
We have both here - diet control and dentals (which Ginger is probably going to need again in a week or so :/) - so it is doable.
I think another factor you need to think about here - is your parents. I know how you are often told your mum has given him extra pellets as she feels he's starving and not getting enough. I think you REALLY need to enforce that they CANNOT do that. Thats not helping the situation at all - if they are still doing this.
I really hope you take this as its meant - it's so very difficult to show empathy and sympathy and understanding with text, i jsut really want you to know i want to help, as do others