I'm thinking of getting a White's Dumpy, but need to know if it'll be compatible in same terrarium as my other 2 tree frogs

I have a female green tree frog (who was in same tank at pet store as Dumpy) and a male Pacific Chorus frog. The green frog is 2 inches and the chorus frog is 1 inch. I know Dumpy's get about 4 inches big and I"m wondering if that should be a problem. The one at the pet store looks fully grown or close to it (3.75-4 inches).

I've had my chorus frog in tank with California toad (3 inches) and she didn't bother him or try to eat him. I've also heard Dumpys have toxins that can be harmful to other species. Would you recommend placing Dumpy in with other 2 tree frogs, since they already have same environmental needs, or would you recommend getting his/her own terrarium? My personal opinion is that they'll be ok (as is the pet store owner who is a frog expert), considering the Dumpy was housed for a long time with the green tree frog that I just purchased-never a problem. Since they're pretty sedentary and sleep most of time on the glass, I don't see a problem. Any input would be appreciated. And since I'm seriously considering buying him/her, any thoughts on determining sex of this species? I've heard males have dark toe pads...thanks!