Quite a common offer if you don't get a 5 weekend/4 spends $XY get 10K points. With the min spend for those offers being $50 that works out at 2,500 points for each $50 spend (but only if you make all 4 instalments), so a rate of 500 points per $10. Taking up the $30 offers see you getting 400 points per $10. So if you take up each offer you end up getting 2,400 points for a $60 per week spend vs the $50 2,500 point offers...
Make sure you spend as CLOSE as possible to the $30 amount, not $40 or $50 something. If you are spending more, then simply cut the order on your card to as close to $30 as you can and put the remaining amount through without FB card.
The things we do to upset the algorithm.
By the sounds of it - you do have totally separate accounts with FBs? One in your name and one in your wife's.