Lighting large group outside with elderly

I'd like to solicit opinions here. This is an outdoor shoot of a group of 16-20 people. What I would normally do for a situation like this is have two strobes with 7" reflectors on either side of me and up fairly high to create a broad swath of even lighting across the group while not having to worry much about the wind. However, in this case, the center of the group is a woman turning 80, and she will be surrounded by her husband, siblings, children, and grandchildren. The 80-year-old woman has asked me to use the softest light possible.

So I've been pondering whether to shoot this as planned and spend some time in Photoshop with the touch-ups, or might I save myself some work if I used a couple of large softboxes/octas with diffusers to soften the light? Anyone out there with experience doing this that could shed some light on it? Thanks.

at a distance to get everyone in frame, fine lines and wrinkles will not be much of an issue.

I assume you'll be shooting them in either shade or sun to their back (or side)….. Either way, use the flash as a filler or fill light (to fill in shadows under eyes and such) so it doesn't matter if you use umbrellas or not (even though that wouldn't hurt) because the two 7" reflectors are still being used as "fill". This technique will allow you to keep the "soft light" required by the client. So just as long as the fill light is meter correctly to match that of the ambient "as a fill light", then you'll be O.K…. but personally, I would get a few helpers and use umbrellas.

Well, they picked the time for the shoot (11am), but it'll be mid-November, and the sun shouldn't be overhead. I will try to get them in shade with the sun providing some accent/hair lighting, if possible. I will try to underexpose the ambient slightly, and using two RX600 strobes, that shouldn't be a problem. While they *might* want some larger prints too, the primary interest is for 4x8 Christmas cards. So I have to leave room to crop the image to 4x8, which means worrying about fine details even less...unless they do want some larger prints that I'm obviously hoping they do. It sounds like I probably won't have a huge amount of work in Photoshop, and I probably don't have the option of helpers. Thanks for the suggestions.