Hello,
Your request is interesting and might be added into HikaMarket as an hidden option.
Since it is maybe too specific and could require more settings/restrictions to be really flexible for HikaMarket users, I don't that as a classical option.
Since HikaMarket do propose the "vendor root" and authorize the vendors to do what they want under that category (even create categories), having such kind of restriction would be complicated for the vendors and could generate unwanted side effects.
Now if you do not have "vendor root" or if you do allow "extra categories", such kind of restriction is clearly good since your category structure won't change like that (and you can use mass-action if one category is no more a leaf one).
I started to work on an implementation, which should be include in the next release.
Afterwards, if you want to have a specific control on product ; you can still use the HIkaShop triggers (onBeforeProductCreate / onBeforeProductUpdate) in order to add you own restrictions and limitations.
www.hikashop.com/support/documentation/6...nBeforeProductCreate
Thanks to the API (which is also triggered by HikaMarket), you can have your own algorithm and also make the difference between the front-end and the backend (admin / vendor).
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.