John M. Donaldson (January 17, 1854 December 20, 1941) was an American architect and artist born on January 17, 1854, in Stirling, Scotland. Donaldson was principal designer of the successful Detroit-based architectural firm Donaldson and Meier from 1880 onwards.

Based on the paragraph above can we conclude that "Donaldson worked for a number of companies before becoming the principal designer for Donaldson and Meier."?
It's impossible to say