I agree with LLL Reptile and Heather about taking your time before adding a new resident. It's a valid and wise precaution.

I will also add (and here's where I get unpopular with the orthodoxy), that I have kept grey tree frogs with american green tree frogs several times over the last 30+ years with very good results (see my avatar). I am not the only one with this kind of experience though others may try to convince you to the contrary.

I would not however add the White's to your mix. Different environmental needs and they get big!