Unfortunately very few of us here know PTO, but you might find a Lacerte user who can point you in the right direction since they use the same back-end calculation.

In the meantime, see if you can find a place to enter box 6 on one or both forms 8889.  You'll choose how to allocate the $7,100 contribution limit between the two spouses such that neither is over the limit.  That allocation goes in box 6 of their respective forms.