Hi,
In HikaMarket you can restrict the categories for your vendors. You can assign them a "root category" and you can give them "extra categories".
By doing so, you can restrict them to their special vendor category which can be outside your classical product categories.
So when they will create a product, the default category will be their vendor category and they will have to select other categories to make the product visible in the front-end store.
You can also choose the "product template" which can provide default (pre-selected) value when a product is created.
In the product template you can select categories which will be the default value during the creation. So event if the vendor does not change them, the value would be more coherent.
Another solution would be to use a custom plugin in order to exclude (refuse) some categories for your vendors.
In such plugin (which use an HikaShop trigger) you can simply refuse the saving of a product if it uses some specific categories.
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.