Now we may know why Michael Lohan was hanging around Lindsay Lohan's set yesterday -- to butter her up before today's bombshell dropped about her so-called mystery sis!
Michael wasn't too happy to talk about his possible bastard daughter from an affair back in 1995 -- when he was still married to Dina -- but it's definitely time to get outta L.A. and get a freakin' paternity test already.
Lindsay's Illegit Sister -- One Mo' Lo?!
6/27/2008 7:46 PM PDT BY TMZ STAFF
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