SWBL needs to figure out what size schools it wants to be involved with. There is too big of a range right now. Either go smaller and lose Bellbrook, Franklin and Monroe, or go bigger and lose Madison, Carlisle, and possibly Waynesville. Waynesville is interesting because they could compete in some sports maybe not football consistently. Brookville is interesting because they seem to be very rooted in "tradition". I think they should leave the SWBL if the league goes bigger, I'm just not sure they will.
If Brookville does look elsewhere, the TRC is an obvious choice. I wouldn't kick out Lehman or Troy Christian to make it happen, but both of those schools concern me with football numbers. If one of them drops football, Brookville would be my #1 choice to replace them (followed by Fort Loramie, Greenon and Northwestern.) I don't see Oakwood as a TRC school.
Your statement about the SWBL being all D2-3 schools though...VV and Eaton are d4. I think Eaton will balk at being the smallest school.