Deductions & credits

So to be perfectly clear, I have been covering my wife with my employer's family plan. It's just me and her, no other dependents on the plan. I have been contributing the maximum family amount plus my $1000 catch up. The fact that she is on medicare has no effect at all on my ability to contribute up to family limit? Others have told me that because she is on medicare i can only contribute up to the single limit even if I have family plan coverage. So which is what I am actually allowed to do, family limit or single limit. thank you for your time.