I have noticed down at my local shops, that some one has put up a sign outside the supermarket "Walkers wanted". then list who your looking for - other mums/dads with kids/prams, no pets/pets - what time you would want to meet and how long you want to walk for.
I am not part of it, but the group no has about 10 people - all who were complete strangers, that all walk together 2-3 times a week.
The sign was just a hand written A4 page. - this might work. They wont all be lovely Minti members, but maybe you could introduce then to Minit during one of you future walks.