Hi and welcome
Your kids sound pretty active and just the sort for this stupid stuff
Yes, I believe 7 league r not available in this country anymore at the moment.
As for adult or kids models.
it actually gets a bit complicated where you are concerned. Forget, for the moment, spring weight ratings.
The childrens/adult stilts in reality refer to the persons height.
The childrens stilts besides being designed for a shorter person are also designed for a lighter person, in that the stilts themselves are light in weight.
The adult stilts r quite a bit heavier than the childrens ones. This means that whilst one often can get a younger person on these, the things r just too heavy to more than clumsily lurch across the ground. Whilst at the same time the childrens stilts might only be of use for a few months b4 the person has sprouted up enuff to make full use of adult stilts and will just not want to be seen ded on kids springs!
Getting hidiously complicated isnt it
To make things a little worse, your children ( with wot 3 months till chrimbo) seem to exactly straddle the children/adult height guide and with just about no margin!!
For the oldest, go for adult, lowest weight. Mention has been given to a 'modification' The thing is 5'1'' people run the risk once happily bouncing about of hitting their thighs on the top of the springs..and not noticing whilst merrily jumping about...but once home it will be 'arrgggg' and really horrible bruises..so a simple solution has been hit apon, simply put a foam block on top of the foot plate for 6 months or so to raise the guy out of the 'danger zone'. Its in the mods section
SO 4'11'' that is 'just' below adult. So what to do? The thing is this is a great and fun sport... but if the wrong advice given a person will be put off for life! You seem to have a reasonable budget and we have steared you to cheaper projumps, so have to ask..when r birthdays? cos sweetest answer maybe get kids stilts bounce about of them, leading to a migration to older siblings stilts then the bigun's for a birthday pressie.
Also where r u? there is always the possiblity of a 'try out' borrowing from some1 in your area