Issue

You want to be able to only allow a cell to be edited or entered only if other cells have data in them


Solution

Pending clarification of requirement, the following might suit:  

=NOT(AND(ISBLANK(S3),ISBLANK(W3)))  

with Ignore blank UN-checked.  

SU536862 example


=NOT(AND(ISBLANK(S3),ISBLANK(W3)))  Would mean Cells S3 AND W3 would have to be empty to RESTRICT EDITING Cell W3=NOT(OR(ISBLANK(S3),ISBLANK(W3)))  Would mean Cells S3 OR W3 would have to be empty to RESTRICT EDITING Cell W3


Link

http://superuser.com/questions/536862/data-validation-require-nearby-cell-not-be-blank

https://trumpexcel.com/conditional-data-entry-in-excel/