This is to share the information of another possible problem in dealing with multiple 100K promos.

To safely credit flights on a single ticket to different accounts it seems preferable not to give a FF number at flight time but to send in the boarding passes afterwards.
Here is a possible problem in doing so.

To credit a missing flight to my QF account I sent a copy of a IB boarding pass and a ticket copy of my oneworld RTW to Qantas.
The ticket had twelve flights on it. Half of them were already credited to QF the rest went on a BA account.

Today I received a letter from Qantas saying that they have tried not only to credit the IB flight but also all the others!
Luckily they were already taken by BA. This would have spoiled my double bonus.

My recommendation is to send in ONLY the boarding pass to avoid this situation. Hope this helps others.