I agree with raybestos and LeoG. I don't think the FCC would agree that 4 hours' distance (or any specific distance) renders a station inaccessible or uncontrollable by the licensee.
Another illustration: Let's assume that you're out with many family members hiking rough terrain divided into several different hiking parties, and that you, the licensee, have handed out radios to each party. While hiking, it's plausible that these family parties may find themselves in locations that are located multiple hours away from you by foot--the only means of ground travel--and yet still be within GMRS range of you. You obviously no longer have direct "access to and control over" all of the stations, yet surely even the strictest interpreter of the FCC rule would agree that this is a legitimate use of the your radios by your family. Therefore, the FCC does not intend your "access to and control over" the stations used by other family members to be immediate or direct. (Although one could argue that the FCC intends the family member's use to be only in the presence of the licensee, this would be pure speculation since the rule doesn't say that, and surely the FCC doesn't intend to allow the licensee's family members to use the radio to talk to anyone except the licensee, which would be the case if the FCC required the licensee to be physically present and thus have no need for GMRS communication.)
Since GMRS range is limited, in the absence of an FCC definition of "access to and control over," it's reasonable to conclude that any GMRS licensee has access to and control over all radios he/she owns that are in the possession of family members related to the licensee as specified in the rule, as long as they are within the normal GMRS range of the licensee using accessible repeaters. (I say "normal range" because if there's a reasonable hope of contacting each other via GMRS, then the FCC is unlikely to consider the distance to exceed the limits of "access to and control over" just because there happens to be an RF shadow between them, or a repeater goes offline, or whatever.)