Opening Forms from Subforms

[Van T. Dinh]

For the first one, I would use:

[Forms]![FormA]![FormB].Form![Unique ID]

but if your existing reference works fine (as it should),
no problems.

For the second reference, try:

[Forms]![FormA]![FormB].Form![FormC].Form![Unique ID]

HTH
Van T. Dinh
MVP (Access)