Pds route:
From lindaret to Ardentb
Down the road. Switchbacks, avg 9% or so
At Ardent the pds route is diverted down the road to the end of the lake as they are working on the bridge and track that goes to Les albertans from up Valley.
However you can get on to the double track (flat and level) at the upstream end of the lake.
At the downstream end of the lake you can get back on the pds route along the river, la dranse. This is a broad rocky track that steepens at times, before becoming easier and then out onto a quiet road. but based on Stoner #1 (8yr) Jr’s woeful skills from taking after his old man, I it’s v doable for 7-9.
After that, follow the pds sign past the gendarmerie then for returning to Morzine you can stay on the right bank of the river to town but I reckon it’s nicer riding up the left bank having crossed on the footbridge at the montriond football pitch. 4yr old Stoner#2 he can happily ride from there to town, All this should be easy enough to follow on geoportail. But if you still have qus, post or email when you get out.