On a serious note, please try to not have your relatives clean or alter the bike too much from it’s as found condition.
Take that process very slow, and let your initial enthusiasm subside a bit before you do anything to the bike.
And if the bike has to be hauled in an open bed truck, cover the saddle with a shower cap, and strap it upright like you would a motorcycle.
I would love to see it in its as found condition if possible.
Plus, it would be good for a family album down the road.
This may be a tangible legacy of your family history.
Pretty cool way to remember those who’ve passed and to give to those yet born.