Follow up on MIL question

I have a question about the following:

“You believe that wanting her to talk about things is a boundary issue. When in reality, it’s a manual issue.

The reason you’re struggling to decide how it is you want to show up with your MIL is because right now, how you show up with her is conditional upon her behavior (i.e. whether or not she’s willing to talk, the things she says or does). You have a manual that you want her to follow in order for you to determine how you show up.”

Yes, I do have a manual. My thought is, if I let go of this manual, that means I won’t stand up for myself and have healthy boundaries. I believe that having the manual protects me from codependency on my part.

My follow up thought is that if I develop boundaries I like with consequences I feel good about, I can let go of the manual. Is that true?

I’ve always ended relationships with people who aren’t willing to address conflict. That’s easy for me with friends or dating. Being willing to talk through conflict is a minimum standard I’ve set up for my romantic partners and friends in the past. I’m not willing to completely cut off my MIL because of other dynamics and relationships. It’s not how I want to show up in that family in a broader sense.

I feel like my brain is struggling to find behavior that’s not based on her actions.

She’s willing to talk -> I can allow myself to open back up to her.
She’s not willing to talk about the conflict -> We don’t have a relationship with any communication.

When I think about how I would want to show up no matter how she acts, I draw a blank. Like, I only want to show up in certain ways based on how she’s acting. Which just proves the thought true that I allow her actions to manipulate me (manipulating myself).

But how else does a boundary function? I have other boundaries that are more definable. Like, “If this family member hits a certain threshold of drunk and acts in xyz way, we leave the family function.” We don’t have drama about it. It’s clear. We still love that family member and everyone else there. We just chose not to be around that family member when they start acting a particular way.

I don’t know what a boundary would be in regards to someone giving me the silent treatment. Like, “If you chose not to work through conflict, I chose not to ever have a certain level of intimacy and closeness with you?”