Surely there has to be something worse than a weekend visit from the in-laws. Well, there is, but its not death or taxes. It s a permanent visit from the in-laws. And in his play Squabbles, Marshall Karp has dreamt up the worst-case scenario. Its quite enough that Alices grump of a father, Abe, lives with her and her husband, Jerry. But when Jerrys mother, Mildred, moves in, the battle begins. The question is: Do the in-laws really loathe one another that much? Or are they merely masking their affection beneath a guise of incessant quarreling? Either way, it makes for a strange mix of The Odd Couple, All in the Family, and The Brady Bunch. Squabbles opens Thursday and runs through April 30 at Sugar Sand Parks Willow Theatre (300 S . Military Trl., Boca Raton). Tickets cost $12 to $14. Call 561- 347-3948.