How to sync a subset of Address Book contacts only

Question

Is anyone able to tell me how to achieve a complete two-way syncing between my phone contacts and a group (subset) of contacts in my Mac's Address Book?!
I have in my computer's address book two sets of contacts:
1) contacts I want to be mirrored in my phone contacts
2) contacts I want to keep in my computer, but NOT in my phone
For this reason, I created a specific group called "mobile" in my Mac's address book. When syncing with my phone using iSync, I would have a full synchronization between this "mobile" group and my phone contacts.
I have carefully selected this specific group (instead of "all contacts") in iSync preferences for syncing my phone, but there is a problem:
when iSync detects new contacts I added in "mobile" group, these contacts are copied into my phone correctly
BUT
new contacts added in the phone are recognized and copied into my Mac's address book WITHOUT being inserted into "mobile" group!!!
This means that every time new contacts are copied from my phone to my computer, I have to move (better saying "mark") these new contacts to the "mobile" group manually, because they are synced but added OUTSIDE the group.
This is really annoying and would make me lose contacts easily from my mobile phone in case of a restore of my phone contacts after resetting or changing the phone (all contacts would be maintained in my computer's generic address book, but not transferred back to my phone).

Answer 1

new contacts added in the phone are recognized and copied into my Mac's address book WITHOUT being inserted into "mobile" group!!!
Although annoying, that is how iSync works, and always has done.
New contacts added on the phone are not put in the selected group for syncing.
In the options for your phone in iSync, you'll notice that whereas there is a "Put events created on phone into: {calendar pop-up}", there is no equivalent "Put contacts created on phone into: {group pop-up}".
This has always been the case, and despite reporting it to Apple many times, it seems to be something they don't want to fix.