Here's what I would do if I were in your shoes.
I'd have the whole gang walk to the cable car station at Murren and look at the monitor inside to see what the conditions are at the top of Schilthorn. If it's in the clouds, you'll have to change plans and maybe all will go on the Children's trail.
Now if it's a blue sky day and you're sure the Schilthorn is clear, then you can split at the Coop store in the middle of town. If you look at the map here, you see what's where:
this city map comes from the Murren brochure found here:
Ideally you both have phones to check on timing, but you probably don't, so I would allow at least 2.5 hours before meeting back at the cable car station. (There are lots of seats there, inside and out, plus bathroom downstairs for the kids.)
The guys can go up to the Schilthorn where there's a restaurant, and James Bond videos, and also stop at Birg, where there's other activities. Women and kids go uphill from the Coop store to the funicular to Allmendhubel, go up, play at that playground and pet some cows up there, then take the Children's Adv. trail that goes counterclockwise from there. (Look at map.)
There's another playground in the woods between and below 040 and 041 that has a neat zip line and other equipment. After that, there's lots of trails down, but easiest to just take the trail straight down the hill that is parallel to the cable car. If you time it right, the guys coming down on the cable car would be able to look down and see the rest hiking down almost straight below them.