How to assign Strategies to part of Customers?

Hi,

We have +10,000 Customers in the application R12.1.3 but we are willing to apply Scoring/ Strategies to part of these customers only (~1000). Is here a way to handle this?

Moreover, there are old strategies already assigned few years ago but Advanced Collections functionality was not used by the company. Now we are trying to use new strategy for the specific list of customers so 1) we have to purge assigned strategies and 2) we need to assign new strategy to a list of customers.

Please advise on these questions.

Thank you

Linas