Gauge Families
The actual interpretaion we were using as both a QS-9000 certified supplier & an independently certified laboratory within the supplier to ISO Guide 25 was a little more strict - a gauge family was the set of the same gauges. For example, all 0-6" Fowler digital calipers, model # xxyyzz. A different brand, different size/range such as 0-12" meant it was part of another gauge family and MSA needed to be done on both families. And yes, we verified different accuracies and such in MSA's with the same employees depending on the manufacturer of 0-1" micrometers, and yes the MSA's for the brands were relatively repeatable. (NB - going on memory as I've changed employment since then.)