hi maybe we can make some new changes in front site also for multivendor update ,
when we save multi vendors to our system we will save multivendors company all info to system and we will map all products from multivendors to categorys, we can make multivendor settings page in admin and if we make multivendor font site suport enable ;
1 - customer can see multivendors company names in front site (same as many shops in 1 web site store )
2. when customer click on multivendor name , front site can show all products from clicked multivendors but left side category navigation will show only category names which mapped products for this multivendor , because we can have 5.000 category in system but multivendor can have product mapped only for 3-4 category
if we can use this , it will be N limit shop in shop , and multivendors can open own shop in our web site and it will be very easy to follow and see all own category and products from front site .