I am assuming that she had worked enough on her own social security record to receive social security disability on her own record. If she married she would continue receiving this small amount. You stated that she is also receiving SSI. If she married, she might continue receiving this depending on her spouse's income and resources and their living arrangement.
If she goes on your social security record as a disabled adult child, then she would still receive the small amount on her own record and the higher amount due off of your record. If she married, then most likely she would stop receiving off of your record and only receive off of her own record. It is possible that she might continue receiving off of your record, depending on if the person that she is marrying is receiving certain types of social security benefits. https://secure.ssa.gov/apps10/poms.nsf/lnx/0300203035
Please look at 3. Marriage here. Most likely she would stop on your record and only receive on her own record.
Sorry it took so long to get back to you. I had a busy weekend with my 5 yr old granddaughter. Good luck with everything and it sounds like your daughter is getting her life back together. Hope all goes well.