Bobbi Kristina -- Browns and Houstons Gather For Bittersweet 22nd B-Day

Bobby Brown was the one given a gift on Bobbi Kristina's 22nd birthday ... he was allowed to gather both sides of the family together to celebrate her special day.

Sources close to the family say Bobby and his wife, Alicia Etheredge, were allowed to invite several members of the Brown family to join them, along with the Houstons -- who've been at the hospital every day -- for Bobbi Kristina's birthday vigil.

Tyler Perry and Bobby's brother Tommy were among the family and friends who joined them at Emory University Hospital Wednesday for cake and some semblance of normalcy during this difficult situation.

As you know ... Bobbi Kristina was found submerged in her bathtub on January 31 ... and has been in a medically induced coma and on life support ever since.