I am looking for a collaborative music recording app for the iPhone. I found Spire Music Recorder Studio from iZotope, Inc., which looks like this:

It allows you to create multiple "layers" or whatever you call them (tracks in a song), the "rows" in that image, and overlay them. However, I couldn't figure out how to do the following with this app:
- Copy and replicate a chunk of a track. I want to make a loop from a track, and copy it multiple times to make the song longer, repeating a beat for example. Didn't seem that was possible.
- Share and work on the song with someone else. I want my friend/teammate to be able to download the app and modify my tracks I laid down in a song/recording, and add their own new tracks to the overall song. This way we can collaboratively build a song together, with simply your voice and the built-in iPhone voice recorder.
Ideally, 2 or 3 of us in separate parts of the globe/world could pass the song back and forth and add/subtract/modify pieces of the song, just recording a rough draft with our voice (like doing beats with beatboxing, melodies with humming, etc.), or if we are fancy we can record rough draft instruments too through the iPhone microphone.
No need for quality mixing and mastering, the goal for me is to be able to collaboratively make a rough draft of a song with a few other people through the iPhone. Do any apps like this exist (free or paid)?
I really like the basics of using Spire, but it doesn't seem to have these features I am looking for (copying/replicating portions of a track to create loops and extend clips), and collaborating. I can share the individual .wav files of each track in a song, but then they can't be easily imported and laid out again as tracks/rows in Spire, and it's a very cumbersome workflow.
Does anything close to like what I'm describing exist? Any audio recording where I can layer multiple tracks which can be collaborated on / shared is enough. Being able to copy portions of a layer to replicate it would be bonus.