I hardly find any discssions where it involves children, in a poly relationship. Hence my observation.
In any relations between the sexes, children must be an issue. How are the children to be taken care of. Infact there is a tacit understanding that care will be taken to remain childless with a poly partner.. whereas in walking marriage it is a straightforward thing.
In the Mosuo community the children are taken care of - as a given - without any condition whatsoever. Also all other aspects like economic and social aspects are amply taken care of. In contrast poly life is a lonely adventure.
I wouldn't compare the two. Each has its plusses and minusses. But on the face of it I think (with the limited knowledge, I have) walking marriage is more appealing to me as it contains the elements of polyamory with other social and economic aspects.
Walking marriage ... I would define it as 'poly with a difference'.
Thank you for the references to the two other discussions on the NA community.