I would not mix species of frogs. Your running frog's scientific name is Kassina senegalensis and native to Africa. This species is much larger and could pose a threat to both the reed frogs and the green tree frog.

A note of caution: Without a photo, I cannot identify the species you have. I do know that there is one species, Kassina maculata, that secretes a mix of powerful poisons from its skin. It would be a good idea to take some precautions when handling the frog.

I have cared for hundreds of reed frogs at the zoo I worked at. I can tell you that they are awesome and are really easy to keep and breed.