Build up to the stay with visits that end well
A dog dropped for weeks into a house he has visited once will spend the first days stressed, however kind the relatives are. Start with short visits where you stay too, letting him explore the rooms, garden and resting places at his own pace, and leave while he is still relaxed. Progress to leaving him for an afternoon with your relatives running the show, then to a single overnight, before the renovation forces the real stay. Each step teaches him two things he needs to know: this house is safe, and you always come back. If any step goes badly, perhaps he cannot settle overnight or reacts to a resident pet, repeat that step rather than pushing on, because the full stay will amplify whatever the rehearsal revealed.
Send his world with him, not just his lead
Familiarity is portable if you pack it deliberately. His own bed, unwashed for the move so it carries home smells, his usual food in measured supply so his stomach is spared a sudden change, his regular lead and coat, and the toys he actually chooses at home should all travel with him. A worn item of your clothing in his bed helps many dogs settle at night in a strange house. Resist sending everything freshly laundered and new; the point is continuity, not a holiday gift set. If the stay will be long, arrange how food will be replaced with the same diet rather than relatives substituting whatever is convenient partway through, because a mid-stay food change plus a strange house is a reliable recipe for an upset stomach.
Brief your relatives on the dog you actually have
Family politeness often softens the truth, and that helps nobody. Tell your relatives plainly about the behaviours they will meet: how he greets visitors, whether he steals food from counters, what frightens him, how he is with children, other dogs and cats, and which rules matter for safety rather than preference. Walk them through his daily routine in order, feeding, walks, garden breaks, evening settle, and show them his cues and how he asks to go out in a house whose doors he does not yet know. Cover the vet arrangements too: your practice's details, what to do and who to call if he is ill or injured, and how costs will be handled so nobody hesitates in an emergency out of awkwardness about money.
Check the relatives' home through your dog's eyes
Walk the house and garden looking for the gaps your dog will find. Gates that do not latch firmly, low fences he could clear when chasing a squirrel, cleaning products or medicines within reach, and rooms where a nervous dog could be cornered by well-meaning children all need sorting before he arrives. Renovation creates a second risk at your end: relatives may bring him to visit your house out of kindness, exposing him to dust, tools, open walls and escaping routes through doors held open for builders. Agree clearly whether visits to the building site happen at all, and if they do, that he stays on a lead, in finished rooms only, and never during noisy or dusty work.
Keep contact steady and plan the return home
Agree a rhythm of updates that suits everyone, a photo or message most days, so you are not anxious among the dust and your relatives do not feel inspected. If problems arise, such as your dog not eating or clashing with a resident pet, hear them early and problem-solve together rather than letting relatives struggle silently to avoid worrying you. When the renovation finishes, reintroduce home in a calm moment, let him investigate the changed rooms and smells on a lead first if major work has altered layouts, and expect a few days of re-settling even though he is home. Handing your relatives a KinsLe Care Pass for the stay gives them temporary, clear access to his routine, vet details and quirks in one place, so their kindness is backed by information whenever they need it at midnight.