Upgrading a dual sport bike - a geometry question I want to ask a somewhat general question in the context of actual events: I picked up an Evo Swift Ridge 7 for about 200 from a discount retailer, thinking it might be a good platform for upgrade-as-I-go. Second wheelset for dedicated XC, wider bars, lose the triple crankset, etc. Of particular concern regards upgrading the fork.

OOTB it comes with an Evo branded Zoom fork with 60mm of travel. I'd feel more comfortable with higher quality fork. 

Will adding a 100 - 120mm travel fork throw off the ridability of a dual sport setup? With the intent of making this both more trail worthy as well as usable for family bike rides?

TIA!
That bike is what it is, a great urban and light trail machine built to a price point. You got what you paid for. Get out and braap. 

Most worthy upgrades like wheels, drive train, brakes and suspension will cost the same or more than you paid for the whole thing originally. So don’t spend any more than you need to cover breakages/maintenance.

The limiting factor in that bike is geometry aligned to a 60mm fork and a bargain bucket grade aluminium frame that will be relatively heavy. A fork with 100mm travel will likely throw the geometry out too far.

Treat that bike well and save your $ to buy at least a “comp” level bike from a well known brand if you decide you want to ride more off-road.

The lowest end of most name brands trail ready model lines include quality SRAM Eagle or Shimano Deore components with a decent air suspension fork. The frames on those bikes are often the same as the high-end version and are worthy upgrade projects. Clearance previous year models will be available at a great price. 

Even though all working bike maintenance is a money pit, to upgrade that bike will be “putting lipstick on a pig”.