List library control automatically populates/links all items in child list where lookup field is blank

I have a child list, "Actual Expenses", that includes a lookup column to link it to an item in a parent list, "Budgeted Expenses". I don't necessarily want every item in my child list, Actual Expenses, to be linked to an item in the parent list, Budgeted Expenses; it is not a required field. In my parent list, Budgeted Expenses, I want to be able to open an item and quickly view all of the linked Actual Expenses items, so I've added the list control to my parent list form to show those linked items.

However, if I try to add a new item in this parent list form for Budgeted Expenses, in the list control for Actual Expenses, it will display all the items where the value in that lookup column is currently blank. And then if I save that new item in the parent list, it automatically updates the lookup column for the Actual Expenses items to link to this new item. I'm not sure whether this is expected behavior or if this is a bug-- and if it's expected behavior, how do I prevent this from happening? When I create a new item in the parent, Budgeted Expenses list, I don't want it to affect/link the items in my child list where the lookup column is blank.

Any help is appreciated!

Hello @jtuckersage,

This is as designed. When a child list is bound to a parent list using the lookup field, all items in the child list must be linked to the parent list items—lookup field is automatically populated. Thus, when a user creates an orphan item in a child list, it will be linked to the parent list as soon as the user saves the parent item—lookup field is automatically populated.

The only way to prevent this behavior is to remove connection between parent and child lists—set Lookup Field property to (None):

Okay, thanks. In my use-case, I want to link items from a child list to a parent list, but not necessarily link every item. If I leave the lookup field blank on the data source editor, I assume I could then just use some javascript to filter the list to only the items where the lookup field on the child item = the currently opened item on the parent list?


You can try out the approach described in Pass SharePoint values to a dialog form article to bind the child item to the parent when it is created from the form.

And you can set up a static filter for List or Library control.