I'm going through this EXACT thing with my lion head brothers. They loved each other in the litter and were always together and we loved them both so we took them both. They were inseparable when they were young, then puberty happened and the both became little a**holes. So we separated got them neautred waited a few months after and now we're re bonding. I'm a few steps ahead of you so this may be helpful. Also, in my situation (dont come at me) we do "bunny swaps" one is free roam and one is in the cage, we swap in the morning, when we get home from work and before bed. (A lot of swapping, kinda anoying) so both their scents are all over the house and they technically share 2 litter boxes (one in the cage and one out) anyhow I started my bonding sessions in the bathtub which is a neutral area and help stop the dreaded tornadoes charging or chasing because I can't get traction, I would put them side-by-side and if they moved I would put them side-by-side again to the rescue sessions to rub each other's scent on each other. Then I put them in the bathtub together with some preferred treat of both of theirs sped along the bathtub bottom. They would snack away and sniff each other and if one nipped at the other I would clap my hands or make a loud noise which would stop that aggression most often, if it did not stop that aggression I was wearing oven mitts (protection for you) and I would separate the rabbits and immediately put them side-by-side again restricting any potential to fight. I started with 5 minute sessions and when they did well I went up to 10 minutes and when they did well I would have been 15 minutes and then after I was at 20 minutes sucessful in the bathtub I moved to the whole bathroom (I would mop the floor with a deodorizer like pinesol, let the floor dry then do a bond) I would start with a 10-minute bond in the bathroom then 20 then 30 then 40 then 50 then 1 hour. Once that was successful we move to the living room which was very stressful because there's a lot of territorial things there the litter boxes the food the water Etc. I organize my living room in a way that if they did get into a fight they could not get behind something I couldn't reach, preventing me from breaking up a fight. This is where I would start from 20 minutes again an increased by 10 minute increments until you're up to 3 hours then you should technically be good to go.
When I'm doing my bonding sessions I have stayed at one time block for a couple of different bonding sessions before moving on to a longer time block. You need to gauge your rabbits and see how they're doing they may be doing better than my rabbits did or they may be doing worse you'll find when you switch environments you'll be taking a step back in the amount of time they will hang out which is perfectly normal. You want to break up any potential fights as soon as possible to prevent too big of a set back. I understand any rabbits can be bonded unless it's a particularly special case some bonding may take one month some bonding may take a year. I have been working at bonding my rabbits for about 2 months now and I am having success we are at the living room stage and they have hang out with each other for about 2 hours. They still have tiffs and are learning to trust each other. They're also learning that they only get treats and preferred foods when they're being good with each other as you may already know rabbits are very food-driven.
GOOD LUCK!
