I have searched through the MSA manual, and whilst I can't say that I have read every single word, I can't find any reference to families of gauges. Miner mentions them in one of his blogs.
Free - Miner's MSA "Blog" Series
Other than that, I can only find a document on the internet, "Ford Motor Company Customer-Specific Requirements For Use With ISO/TS 16949:2002
http ://www .iaob. org/pdfs/FordspecTS2nd_December 2007.pdf - DEAD 404 LINK UNLINKED
Page 18 states
Measurement systems analysis (ISO/TS 16949:2002 cl. 7.6.1)
All gauges used for checking Ford components/parts per the control plan shall have a gauge R&R performed in accordance with the appropriate methods described by the latest AIAG Measurement Systems Analysis Manual (MSA) to determine measurement capability.
Any measurement equipment not meeting the specifications stipulated in the MSA must be approved by STA.
Use of family gauge studies per the MSA is permissible and must be approved by STA
Where STA is
"Supplier Technical Assistance – Ford Motor Company's team dedicated to assist in the development of supplier processes.
I don't know if this is a unique Ford concession, or if it applies more widely. Perhaps Miner could enlighten us?