Move an editing form to display a selected field value that is on the subform

[mmaule]

I need to move an editing form, that has a subform, to display a selected field value that is on the subform.
I have two tables:
StatusMnemUnit with fields:
SMU_ID
System
MnemFileName


MnemonicUnit with fields:
SMU_ID
MU_ID
MnemonicName
etc.
The Relationship is the SMU_IDs.
The parent form displays the StatusMnemUnit info and the subform displays the MnemonicUnit information.
I have a form, based on a query, that allows me to select a specific MnemonicName and edit the MnemonicUnit information, but I can't use it to delete a specific MnemonicUnit record or add a MnemonicUnit.
How can I position the form to a specific MnemonicUnit record so that I can edit or delete the record?

[June7]

Why can't you use it to delete or add record?

If by 'position the form' you mean find a record, options are to filter the form or go to the record.

[mmaule]

I have a form, based on a query, that allows me to select a specific MnemonicName and edit the MnemonicUnit information, but I can't use it to delete a specific MnemonicUnit record or add a MnemonicUnit.
Why can't you use it to delete or add record?
The query combines the StatusMnemUnit and MnemonicUnit information. with this for I have no problem displaying a selected MnemonicUnit record, but Deleting it, would delete the StatusMnemUnit record as well and I don't want that. Likewise, Adding a MnemonicUnit record woule add a StatusMnemUnit record as well and I don't want that either.
With the form I am trying to use for Adding and Deleting MnemonicUnit records, the parent form displays the StatusMnemUnit info and the subform displays the MnemonicUnit information, I can add and delete MnemonicUnit records fine, but there are several hundred MnemonicUnit records per StatusMnemUnit record, so trying to use the navigation controls is too slow. I am trying to select a specific MnemonicUnit record, from a combobox, by MnemonicName, and display it associated StatusMnemUnit info and MnemonicUnit information, so I can delete the MnemonicUnit record. When the form redisplays, it displays the prior StatusMnemUnit record and its first MnemonicUnit record, not my selection.

[June7]

Not really understanding issue. If you are using form/subform, why is there a query that joins tables used as form RecordSource? I can understand enforcing relational integrity, which is what you appear to have set up. The point is you can delete the records but related records would also be deleted. This is fine as long as you understand this. If you want to delete then delete, however, deleting records should be a rare occurrence.