I'd have to agree w/ Wonder - I don't get the feeling of being "one down" from DB'ing. The situation I'm in sometimes makes me feel that way, but I would have to admit that's bec. I so want to 'control' his actions and 'get my way' . . . I think that we feel like we're one down bec. we want what we can't have (just yet...) and are working so hard on improving ourselves w/ our H's as the catalyst for this change. We transfer the 'power' to them - really no one puts us "one down" but ourselves.
When I compare how I felt before reading DR, I realize that DB'ing actually makes me feel like I have 'one up'in the sitch - in that I have tools, ways of thinking, and a whole gang behind me, to work through my issues, my growth, AND my sitch. My SO has none of that (that I know of). I feel better that I can "do" something, that I have lots of advice to sift through and employ when it fits.
---- I also agree that if you are asked you should indeed attend BIL's service, if that's what you'd like to do. It's your feelings that matter most right now, and you should listen to them and decide what's best.