Sources tell TMZ Michael arrived at BF on Monday and has been there throughout the week as part of their family week. We're told in the early part of the week, Lindsay and Michael each went through therapy sessions ... but not with each other.
According to our sources, the two began doing sessions together on Wednesday. One session simply included the two of them and a counselor -- another session involved a larger group.
We're told counselors at Betty Ford, as well as Lindsay and Michael, want Dina to join in on the sessions during family week next month.
Sources close to Dina tell us that so far she hasn't been asked -- and that she wants no part of a therapy session with Michael. But reps for Betty Ford tell us they wouldn't have to see each other -- it's S.O.P. to put family members in separate groups.
As for the rest of Michael's week with LiLo... on Thursday night, Michael was spotted out with Lindsay (above) -- we're told Michael treated Lindsay and a few of her friends from rehab to dinner.
And how's this for a small world ... we're told Michael bumped into a Betty Ford employee in the halls that he recognized from when he was a patient there back in 1989.
Circle of life.