To Allow or Disallow Reverse Lookup

Click Insert tab Block Definition panel Block Editor. Find
In the Block Editor, double-click a lookup action in a dynamic block definition.
In the Property Lookup Table dialog box, at the bottom of a Lookup Property column, do one of the following:
- Click Read Only, and then select Allow Reverse Lookup from the list.
- Click Allow Reverse Lookup, and then select Read Only from the list.
Note: You can only select Allow Reverse Lookup if you have entered data in the column.