Transfer CoC from iOS to Android without locking CoC to iPhone

I have an unusual situation. My son has been using my iPhone for Clash of Clans, but never set up Gamecentre. As a result, I understand that his game is actually not backed up anywhere, except for the device itself.

We now have an android device (Android1) that he would like to use. I have a (different) android device (Android2) that has my game on it. I'd like to transfer his game to Android1, and transfer my game to my iPhone so that I can play on both devices (Android2 and iPhone).
I understand that in order to transfer his game, we need to link it to a Gamecentre account. We've set up a GameCentre account for him for this purpose. Once linked, I plan to use "Link a Device" to transfer his game to his own Google account on Android1. I think that part will work fine. The problem, is that I'm not sure what will happen if I log into my GameCentre account on iPhone. Will his game, which would not be linked with his Gamecentre account, also become linked with my GameCentre account?

A village can only be link to one GC/G+. Once linked, no fear of losing it, or overwriting it.

But I think when you'll want to link your to your iPhone, a factory reset will be needed.

Thanks for the response. That is comforting to know that it cannot be linked with a second GC account. However, I'm still at a loss as to how to perform the transfers as I described above. Any advice?

Further to the above, I just tried deleting CoC before linking my son's account with any GC. My thought is that it would not be saved, since it was not linked. However, when I reinstalled CoC, his village is still there. Is there any way to completely delete a village that is not linked to a GC account?

Having kids/multiple accounts/devices/platforms is a challenge sometimes.

Assuming I understood correctly, you want to perform the following:

son: iphone base -> Android1
you: Android2 base -> iphone

1) On your iphone:
- create a GCid for your son, log in, and start CoC so that its now linked to his GCid (welcome message bubble) (NOTE: if he ever started CoC with your GCid signed in, that CoC base will be forever 'mated' to your GCid).
2) On Android1:
- create a Google+ account for him, and sign into android1
- sign into iphone using his GCid
- perform linking of iphone->android1 as per linking guide
3) On Android2:
- create a Google+ account for you, and sign in (in CoC, the gear icon)
- sign into your GCid on iphone
- perform linking of android2->iphone

If you've already (accidentally even) attached your son's base on your iphone to your GCid, you can't perform this. In this case, it's best to continue to let him use your GCid linked with his Google+ account on android1, and create a new GCid for transferring your android2 base to the iphone.

Also remember, once you link 1 GCid to 1 Google+ account, that link is permanent. No other base may be ever attached to either of those two accounts on any iOS or Android device. And now you can open that same base on any other iOS OR Android device.