What the family should do is have the reception anyway, make it a welcome home, we love you, Jenn and John, too, party. The guests, relatives, and friends need to unwind. It would be a good way for Jenn to get over the initial awkwardness of meeting her family, friends, etc.. They'd be drunk, they'd just hug her, no recriminations, etc..
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"You've got to be kidding. Maybe a party . . . no Jenn"
Yeah, an order a Jenn look a like pinata
It's probably BYOB.