Hookpad to iPad Garageband

Does anyone know how to transfer a Hookpad Midi file into iPad Garageband? I can transfer it into iMac Garageband, but I can’t find a way to transfer my iMac Garageband file into iPad Garageband. (The reason I’d like to do this is to lay down a vocal track after modifying the original Hookpad backing.)

If there is an easier way to combine a Hookpad file with a vocal track, please let me know.

Cheers …