I have also done this in the past, domestic for a person with a medical condition (YYZ-YYC) and coming back from VIE for someone I knew was a new mother and was on her way home to a frazzled husband no doubt wanting to pass the child back.

The first time was anonymous, the second time she knew it was me, although I had the kind staff at OS take care of it so it wouldn't come from me. She did figue it out though, as I was the only other one up front she knew.

As for MLL's when entering a lounge if I see a single person kinda hanging around, I ask them if they are interested in going into the lounge as my guest. I make it clear I am not trying to pick them up, in fact I have work to do, but since I am allowed a guest a no charge, I always like to let someone else experience the lounge. Some people say no thanks, but most take it.

Pay it forward