id honestly say no. even if everyone is fine with each other now, you are pushing your luck with the danios and gouramis. they tend to stress a betta out or flat out fight with them..you may wake up one day and find a shredded fish or worse best to have a back up plan in your stocking in case theings suddenly go awry. it might be a good excuse to get a hospital tank anyway. a small heater and a homemade sponge filter will be fine for this.
how long have you had your current stocking and how big is the tank?
cheers
My PK Shimmer shares with 2 German Blue Rams AND and gold gourami. Shimmer tends to keep to himself up the top of the tank in the floating plants and the others dont worry him. But i wouldnt put a long finned betta in there. GBRs can be quiet aggressive, particularly when in "season".