just shouldn't be happening (one cursor bound to one grid causing issues with a completely different cursor/grid)

Agreed... this is 2 separate cursors from SQL server, right?

Maybe there's some rogue code somewhere if the recordsource for the parent grid is being hosed while the cursor remains. If it's happening during the recordsource recreate/restore process for the child grid, is there any declared/inherited code in the object you describe, that assumes the grid name is that of the parent grid? Or is there a property somewhere that needs to be pointed to the child grid?

If none of this is the issue and if it usually works properly, I'd be inclined to rebuild the form in case there is some deep-seated SNAFU you'll never find. I've seen grids act bizarrely more than once- once I remember tearing my hair out over a grid where the highlighted row leapt about infuriatingly as if the recordsource was constantly being tweaked: after many happy hours of tearing, I rebuilt it from scratch... problem solved.