Hi:
Well, it's easier for me to conceptualize this if you also own the PC version. If that were the case, both of you would be able to access it. Both of you would have your email addresses registered to Cloud sync.
Secondly, when you refer to iCloud Sync, I'm assuming you mean MLO's cloud sync.
Once you have the above set up, I think you could both sync your phones to that one desktop MLO.
The reason I think the above is feasible is that I have both my iPhone and Android Tablet synced in that manner.