Expenses: Paying for College when It's Time

My question involves a child custody case from the State of: Washington

My ex and I have 2 children together. In the divorce college expenses are included, and I'm ok with that since I want them to attend.

I have proposed with the ex about paying together into a college savings plan, we each pay our correct portion of whatever the predetermined amount is. This way our children have money for college when they get there.

Here is where my question comes in though. The ex is declining to participate in the college savings plan.

For the sake of ease, we will use easy numbers. Let's say University has a cost of $30k year, out of pocket. After maturity, the college savings plan covers $10k yearly. Do we split up the remaining $20k according to our child support percentages, or would my portion be covered by whatever the savings plan covers?

Or what if the ex cannot afford anything?

Our children are 10 & 6, I already feel we are late to start saving for higher education but the ex is thinking to just handle it then and/or stick the children with the student loans. Yes, sometimes that has to happen but I don't want to start them out with complete debt if I can at least help now.

Thanks for input!

Expenses: Paying for College when It's Time