Use Retayne prior to construction to lock in the dye. Use Synthropol once constructed. Synthropol will not really stop the bleeding it just keeps the dye that has migrated from the fabric from attaching to other fabrics in the water. It does assist in removing excess dye that has not "bonded" to the fibers. If washing with Synthropol make sure you remove the quilt ASAP from the cycle as there could still be a bit of migration if moisture is in the quilt if there are really bad bleeders, because once rinsed the Synthropol is gone.
I use Retayne and then test again to make sure. If it is a known "offender" such as some batiks I have used twice the dosage and gotten excellent results. It is pretty reasonable to use at only 1 teaspoon per yard. But you must get the water temp up to 140 degrees . Once treated with Retayne wash only in COLD WATER.
Using Synthropol requires more , so ... one teaspoon per gallon of HOT water. Anything treated using Synthropol must be washed in warm water 110 degrees.
Vinegar is not effective for cotton fabrics. Some may get results but it is mostly from the water, vinegar will remove most treatments such as starch and sizing used in the manufacturing finishing process.