How about this? You could follow us up in the morning, and then leave when you want and go to your brother's MIL's directly. You'd be practically there on the way home, it'd be a lot of extra driving to come all the way home first. We'll be coming back here somewhat early - hopefully by or close to dark, we can go get Cisco when we get home if you aren't home yet, then you can stay as late as you want.
Ooh...that could work! I'd get the best of all worlds... ;-)
And I could go to my usual church for Christmas Eve, too. I'm curious how Byzantines do Christmas liturgy. Should be nice.