Sounds great! It’s hard to advise the next step without knowing exactly what you’ve been doing so far, but in general whatever you did that worked well, keep doing that for longer (so same location, time of day, etc)! When you see those positive behaviors repeated for several sessions/days in a row, then you can keep increasing the time they spend together. There is a “bonding template” pinned in this section that you can paste in your reply to give us some more info.
Chasing and nipping can be a mounting attempt and/or aggression. If the interactions were not in neutral territory, I would try them in a neutral spot and see how they do. There are reports of buns that hated each other that change their tune after years of living as neighbors!
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.