sorry for not understanding this fully, but....1. As we stated you need to add case ID to the first forms query. Makes is a whole lot simpler.
2. The second subform is linked by CaseID and not Case name
1. i've added CaseID in recordsource to the left subform in below db same as you did, but the vba still gives an error that it can't find CaseID member.
2. With Arrnel, his master txtCaseID is only using this code =[frmKeydates].[Form]![CaseName]. It refers to left subform. When I use exactly same code, it gives me different result.