Like you said, noise is a big one. Perhaps bring noise canceling headphones on trips to your cousins. Also smells, this should only be briefly problematic as a diaper would be quickly changed by your cousin or another caregiver of the child. You also may want to be prepared to leave a room if necessary as some forms of stimming or loud noises from you could set of the baby, but that depends on what your behaviors are. Best of luck to you and your cousin.