The angels, gouramis and tetras should be ok in the 40 gallon, but I wouldn't add more fish to that except perhaps a few small bottom feeders (corydoras or a small plec that stays under 4") or a few more of the same tetras. Mollies as mentioned really do prefer brackish water or hard alkaline fresh water which your other fish won't do well in. As for compatibility, you've likely got two male dwarf gouramis which may be ok in there for a while so long as they have lots of cover, but will likely end up killing each other.
Common plecs get well over a foot and are very messy, I wouldn't keep one in anything under 100 gallons. If you want a pleco, there are many different varieties that stay small and are suitable for tanks as small as 20 gallons. Silver sharks easily get to a foot in length and are schooling fish so you'll need at least five. Because these guys are so active and large, again I wouldn't go under 100 gallons if you plan to keep them. I'm assuming that your parrot is a blood parrot cichlid, which is a hybrid fish that will need at least 50 gallons. I've actually seen a few of these guys get to a foot long and they're in no way a slim bodied fish. Compatibility here should be fine as far as the parrots and silver sharks are concerned so long as you don't keep them with anything too agressive, except that common and sailfin plecos once fully grown are notorious for sucking on slower moving fish like parrots.
I'd rehome the big fish sooner rather than later, it can be a pain trying to find people who will take really large fish (I've had to do this before, it isn't fun). If you want to keep the big fish and are definintely going for a larger tank soon before you stunt your fish if you haven't already, I'd go for at least 100 gallons to house the sharks (and a larger group of those, they're schooling fish) pleco and parrot with perhaps another parrot or two, they seem to like company.