Anna, I had a mom who relactated at 5 mo.  It took about 2 mo before he was
fully BF.  He received milk bank milk and donated fresh and frozen milk for
supplement to mom nursing.  This was in the days before SNS.  He was willing
to suck and that's the key-baby who will suck at breast.  It wasn't easy for
mom, or me (as counselor/support) or all the moms who pumped, but he did
great healthwise after being totally br milk fed.  It was worth the effort.
We thought he was going to dwindle away and die at that point too.  Dr had
no problem writing RX for milk bank.