Pity these are no longer available, perhaps you can find a used one
:
Polaroid 58mm HD Right Angle Mirror (SPY) Lens PLSPYLENS58 B&H
More serious advice:
1) I focus on being a participant at family events, not a photographer.
2) I use one camera + one lens slung behind my back, typically a 50 or 100 on aps-c. Or a Nikon j1+10mm pancake (tiny, near silent, and good enough quality for many candid situations). Either way, something compact and not obtrusive when not in use.
3) I usually aim for close-up types of photos that the tablet/cellphone people don't usually do (typical snapshots are of a persons head dead centre in the frame and too far away).
4) I do not try to photograph everything, but pick and choose my moments to get photos I'll be happy with.
5) I have been outright ignoring commands of "take a picture of Johnny/Jessie/Insertrelativesnamehere" for long enough that no one bothers commanding me to do things anymore, and family members have learned to be happy with what they get from me. I really think this is critical to my enjoyment of family events. I'm not a professional being paid to perform on command, I'm a participant and no one has any right to expect more.