In re-reading yours -- you will have two separate families using two separate DDE cards. That should be fine. I think they just try to avoid splitting checks all the time.
As always -- it depends.
They use to bend the rules more so than now.
It is one card per table, and no splitting of checks.
So prepare for that in case that happens. And it very well may.
Sometimes I have asked the server if they will split checks and the response is yes, until it gets to the hands of the manager. Then they stick straight to the written policies.
Up until March of this year they were pretty accomodating. Now it is more rare they will do as requested for anything outside if the written policy.
I really don't think it is the servers. They seem to want to do what they can to makle the guest happy.
I had one time where the server said Yes he would split the checks, but then was told he could not. I think he felt bad and allowed the party at our table to use my DH's DDE card.

That was fine with us. But was outside of the rules.
The servers just want guests to be happy, tip well and be in and out.
Yes, they can split tickets and probably about any other requests. Will they? Maybe.
Plan on the written policy, and be happy if you get anything else you request regarding the meal bill.