If the tanks are in the same house, they probably have the same temperature and same water so it's not such a big deal about acclimatising them to the new tank. I never bothered at home or in the shop if the fish came out of similar tanks. I just scooped them out of one tank and put them in another.
Maybe your dad should get his own tank. Then he can set it up however he likes
You can add other species like Corydoras to the tank to add variety. Just find some fish that come from the neighbourhood and mix them up a bit.