Here's todays results from my discussion with my mom:
1. Take said thrifted top and slice it down the middle, muslin lining and all. Also, cut off black ties on the side & set aside for later.
2. Hem and sew the new edges of the robe; careful not to fold the hems too many times as it will ruin the V-neck. I had only 1 fold, which still left raw edges, so....
3. Reinforce new hem and seal raw edges with grosgrain ribbon.
4. Applique the ties that were removed to the new edges of the garment-one on each side.
Also, where ties once were, amend the seams on the sides so the leftover raw edges from the ties do not fray.
5. Sew button & button hole at the waist, flank side of your choosing, to fasten the garment while wearing.