Again Chocolate.. it may not be "recommended" but it is doable and it can be just fine for 1 molly.. 1 molly and 1 betta swimming about a 10 gallon won't be too cramped. I wouldn't suggest adding more mid level - top level swimmers.
As long as the tank is kept cleaned, heated, proper filter, etc then I can see no harm in doing what the poster is wanting.
I can sit here and tell the OP exactly what we believe is the proper way to keep the fish, etc. Or I can sit here and help the OP be able to keep what it is they want safely and healthy. Not here to judge, here to help and offer recommendations.. whether the recommendations are followed or not, it's not up to us and it's not our job to be negative about it.
Breeder so I have too many to count and too many named to list here!