Relationships: get parent by child name in plugin

EE 2.11.1

Not going to try to elaborate why this is the case, but am currently working on a plugin where I have to work backwards from a child relation. However, I only have the child’s name available.

I have been digging around for a bit without success and figured, I would just make a DB query, but the relationship channel data field only reads XHTML.

So, in a plugin, how can I get the Channel Entry/Entries searched by a child’s name in a relationship field?

Happy to buy Playa, if this will help.

Thanks for the continued guidance.