Anything too hard to answer is ignored
Don't give them a choice of questions to answer. Pick one. Make it a good one. Already know the official answers. Don't let them change the subject.
"I'll have to do research on that
Get them to promise it by a date. Remind them. Lots. If they want to start another subject, ask why they haven't answered this one. Make them feel guilty for any trickery they are using to weasel their way out of providing you with the research they promised.
Feign being offended that they would try using such a tactic on their own flesh & blood, spouse, whatever you are.