Unfortunately it was easy to look for distant relatives but now that it is under 100 years access to the archives doesn't help.
Have you done name checks at nasza klasa. pl ....facebook etc ?
There might be some WWII info available: military records, death camp records.
Have you checked old directories (business/phone directories)
Have you placed information on a Zambrów (or nearest town) website or asked for information ?
Have you left messages at ancestry.com or genealogy.com
check your PM's