when/if we go on vacation we would just make sure it wasnt for more than 48hrs.. this way we could drop food before we leave and just as soon as we get home.. perhaps drop extra greens? (yuk though they shrivel after a couple hours) now im not sure about older adults but we have babies right now (2.5mos) so maybe older ones can go a day or so??? i dont know to be honest with you ive always liked tending to my animals daily.. makes me feel like im part of their lives, and with reptiles i think they need constant attention to stay "nice" but at the same time thats my opinion. we did go on a 4day cruise in april but at the time we didnt have any animals to worry about... we really dont go very far (less than 4hrs away) i would have a friend come by and feed them if i had too.. they are easy enough to feed.. could your sister drop some salad at least for them?