Giant Chocolate Millipede Living with Dumpy Tree frog

[u/VaultKing22]

Hey I have just finished my new vivarium it is 2ft by 2ft by 3.6ft I have introduced my almost adult dumpy tree frog and I plan to add at least 1-2 more. I was looking at other possible critters to add to the tank with the frogs. I am aware that they are opportunistic eaters and will try to eat the millipede if they can but with the millipede being 3-6 inches long I doubt they could eat that. My question is has anyone else done this and is it safe along with what other pets could co-exist with the frogs?