modification in multi vendor ext & make b2b add various function as per concept

we want to add functionality in multi vendor extension in magento:2, with connecting API of b2b order processing omni channel, courier,add product in magento [login to view URL] part to be finished first and make operative. then in staging environment,... we want to add credit base buying module, subscription base shopping bucket buying and subscription base seller network (offline to online) where seller can invite the buyer for his own [login to view URL] module will have 5 option to get credit to buy item from platform to registered business [login to view URL] pricing and shipping tie pricing etc. developer must know the tradition credit base business process in [login to view URL] need to work on multi vendor module. support 6 month.