<human>: Can you provide a brief rundown of the text in within 3 sentences?

I've been dating Ann for 3 years and were recently engaged. Everything is pretty smooth except for some minor issues in regards to her son. She has a 5 year old boy Michael from a previous relationship. I love the kid and we get along great. His dad is hardly around and we're basically our own little family. 

My problem is that I'm not comfortable with how much if any say I should have in the decisions on how Michael is raised/his rules. Ann handles all of this, and when she is around I don't interfere, even if I disagree. He is her child and although I love him I don't feel like it's my place to really even voice my opinion on how she's parenting. 

The problem comes with the rule that she has for him that he has to "finish his plate" at all meals. When she is home I don't say anything and let her do her thing. But usually once a week I am on my own with Michael and I just can't bring myself to enforce that rule.

 I've had an eating problem my whole life- and I've had to struggle to lose around 75 pounds in the last year due to unhealthy eating habits. I still deal with urges to overeat and I think it goes back to those same habits I formed as a child. Well of course it gets back to Ann that I don't make him finish his plate when she isn't home and she was upset. 

I tried to explain to her that it's setting him up for unhealthy eating(he's already heavy for his age, nothing major but not ideal) but she sees it as me not supporting her decisions on how to raise her son.   

I don't know how to deal with this moving forward. It's making me realize that there has to be some compromises if all three of us are going to be in the same house the next 15 years. I have to have more of a role than just Michaels buddy and occasional babysitter- but I don't want to step on Ann's toes. I'm not sure how to proceed.
<bot>: Fiancée expects me to uphold rules I feel are damaging to her son when she's not around. Not sure what to do.