obsolete beta,beta digalactosyldiacylglycerol galactosyltransferase activity (obsolete GO:0102996)
OBSOLETE. Catalysis of the reaction: a 1,2-diacyl-3-beta-D-galactosyl-sn-glycerol + a beta,beta digalactosyldiacylglycerol = a trigalactosyldiacylglycerol + a 1,2-diacyl-sn-glycerol.