Not knowing what you're looking for:
- If you want someone else to be doing everything...What you're actually looking for is a governess or private tutor.
- If you're looking for an individual or group to *trade* time with/ help each other out... the term is co-op.
Just like SAHPs don't = free babysitters (can't just say "Hey, you're a stay at home parent, watch my child since you're already watching yours"... but instead have to hire someone or do straight trades) ... homeschoolers don't typically take on the education of other people's children ***unless*** it's part of a co-op environment. Schooling your own children is a TON of work (just like being a parent is a ton of work)... but schooling someone else's child is *easily* 10x the work. In part because of this... most co-ops aren't straight "day trades" (You take Tue/Wed, I'll take Thur/Fri)... but instead offer specific classes taught by parents for specific times (like biology for 7-10yos from 10am-noon on fridays).
MD is something of a difficult state to HS in... requiring either direct supervison of the school district (ugh), or a church or private school umbrella program. Any of the above can make it *very* difficult to hire out, but it really depends on the program. Here're some links that might be helpful in your research:
http://www.hslda.org/laws/analysis/Maryland.pdf
http://homeschooling.gomilpitas.com/extras/Search.htm?cx=... for maryland links in general, including laws, but HSLDA's are (for once) more clear in this case than Ann's