dating websites for learning disabilties

Hi Gill
I have a sister who has learning difficulties she lives on her own and is quite independant with close family near by, we have found out recently that she and a friend who is alot older than my sister who is 36yrs old but has a mind much younger, they have been looking on the dating websites on the internet we are quite worried about her meeting someone they not appear to be. I have spoken to my sister about the dangers and she understands but still are concerned I am trying to find a dating/friendship agency but had no luck so far we are based in Bridgend South Wales any help or advice will be greatly appriciated
Kind Regards