Large family shot

I have been asked by my family to a group shot of everybody. Under normal circumstances I would just kind of wing it because it is my family and if I mess up then there are no real consequences. Unfortunately, we are not under normal circumstances. My mother-in-law has recently been diagnosed with liver cancer. So that, along with a lot of new babies, is the reason for the photo.

That being said, I don't want to mess this up. In fact, if I feel that I can't do a good job I will pay a professional to do the job.

I only have several speedlights (3) and umbrellas. This seems to be pretty underpowered to me. It will probably be outside. So when would you recommend that I take the shot. Midday in full shade and forget about trying to light it? Golden hour (difficult with kids)?

Could I actually light the shot with the speedlights and balance with ambient?

Any pictures of examples would be great. I am really concerned about this and I am throwing myself on the mercy of the forum (and yes I did search and didn’t come up with much).

I've done a group as large as 75 with 3 speedlights no problem. One on camera (bracket) and one each on lightstands to the left and right of camera reflecting off umbrellas. This gave me plenty of even light for the large group. I shot at 24mm which allowed me to stand fairly close to the group and my off camera lights were as close as i could get them to the group without them being in the shot. If they are not delviering then dial up the ISO and open the aperture as much as you dare with a group shot (another reason wide(r) angle lens is good for this type of shot). I think I shot mine at ISO 500 at f/5.6 or f/8.

...oh, and make sure you get plenty of other shots with the mother in law with smaller groups of family members.