when do I get a parentcontext?

• If I have a plugin watching for a many-to-many association to take place, say, account-to-product
• and at the end of that plugin it says go associate these other accounts to the same product (same association relationship)
• do the "child" association contexts know of the first association context as their parent?

I'm asking because I wonder if I can enter something into the first context.SharedVariables that the children.parentcontext.SharedVariables can read to know that they don't have to repeat the child associations for their brethren.

e.g. if ((bool)context.ParentContext.SharedVariables["alreadySpreadAround"]) return; else SpreadAround();