We are in Copenhagen, visiting Europe for 6 weeks .
I pulled out my laptop and had a look at the sample we used; you already pass a pipe-delimited string as the OpenArgs for the f02InvLdgrAccItm pop-up form. You will need to modify that to include the name of the calling form and the name of the subform to hide\unhide and retrieve them using the Split() function like you're doing now for the the other arguments. Then it is just a matter of using those variables in the line used to hide or unhide the subform. If you get stuck please upload the code or a small db sample and I'll have a look.
Cheers,