How to apportion a family HSA deduction, 50/50 or 100/0?

How should a family HSA deduction be apportioned?  This is an after tax self contribution, no employer.

 

I am over 55 so can deduct $8100 per year for my wife and I as a family deduction. I declared it in turbotax as $4050 for me and $4050 for my wife.   I see $8100 appears on 1040 line 10a, but on form 8889 line 2 (etc) only $4050 is declared, and $8100 appears nowhere.   Should I have declared $8100 for myself and $0 for my wife rather than $4050/$4050?