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Well, images are always better--- If I read you right; this should mean that the as-built axes of the four holes must simultaneously fall within a cylinder 1.4 (mm?) diameter.
I assume the calculation you want is the inner boundary of the four holes? This would be MMC size minus the position tolerance.
One would assume that one hole is offset maximum permissible by the position tolerance from the other three holes and this would represent the collective inner boundary.