If the tasks are named the same and the numbers are the same, you can't use a filter. The names need to be unique in order to apply filters. If you only want to filter for one apartment, I'd use a spare text field and copy/paste the apartment names into the text field. Then filter only on those fields.



Another option is to forget filtering and use the ability to collapse all summary tasks quickly - then just expand the one you want.

Finally I used the WBS field.
It works great, even after adding a new task.

New filter>
field name>WBS test>equals value> 1.1* etc...

Thanks anyway

Hillel