How do I enable FaceTime on iPad and iMac simultaneously?

hi folks

i have an iphone15+ an ipad air and an desktop imac . i will be going on a trip and want to facetime my husband home . i have been testing making a facetime call from my iphone to my own cell number . the ipad call will not be received it will go through on the imac . is there a way to have it ring on both the ipad and the imac . my husband may be on the ipad and not near the imac. i have checked all the settings and they seem to be correct thanks for any help

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