Child pulks come up occasionally on this site. I did a lot of skiing with Fjellpulken (both groomed and ungroomed terrain) with our first kid. We had an addition to the family and recently acquired the Thule chariot for 2. This is great so far on groomed terrain and has some advantages over fjellpulken-- but is decidedly less capable for off trail adventures.
The main issue with the Thule is that the stock harness is a simple waistbelt and not comfortable for heavier hauling (esp 2 kids). $5 at the hardware store allows for a simple fix to use a pulk harness with shoulder straps (or attach to a ski touring backpack). Wanted to share and see if any other tips out there.