Two females, ten last names

Did you ever thought how difficult it is to search for the female relatives? Here is an example. 

Our colleague has recently gave the presentation on his experience tracing the artwork provenance of several portraits by Mikhail Verboff (1896-1996). 

Look at the attached picture. Two sisters (lower right corner). One have four last names from different marriages, another have six. 20th century, four different countries. He was able to document it and even trace the living heirs. 

How complicated it was? About a half-year worth of work…. Could he find it without our published Genealogical Index? Highly unlikely, he admitted. 

This is a real-life example of tracing female marriages.