Change our wocommerce subscriptions plugin

Plugins and extensions involved: Woocommerce, subscriptions for woocommerce, groups for woocommerce, wordpress. Background: the curreent live online shop sells one year membership as a product in the shop (set up as a simple subscription product using woocommerce and woocommoerce subscriptions). Once a customer buys this product they are allocated to the subscriptions module, this also automatically allocates to to a group (depending on type of membership). Challenge: At the moment this all works perfectly if you are a new member buying through the shop. The problem comes in when we try and import or manually add our existing membership customers and their old order for a one year subscription through the backend. It comes up as an order but does not flow through to subscriptions plugin or groups plugin. We need this data so that customers, can login, receive the privileges of their group and subscription. We have approximately 2000 existing membership customers spread across 4 membership subscription products. , Requirement: I need someone that can configure our woocommerce subscription module so that I can change the subscription dates. The documentation suggests it can be done, but I can't figure it out . I also old memberships automatically uploaded for all of our current subscriptions so that it flows through from an order into subscriptions and groups in the woocommerce order section and is then visible as a subscription. When I enter a new one manually from the front end this happens as it should. But when I add one from the backend it only comes up as an order not flowing through to the subscription list. I would like someone to help with this ASAP as the website owners need there members to be able to login and renew their subs.