How to best create Original Contract Start Date, Current Contract Start Date & End Date

Hello, 



I am currently starting an implementation of Gainsight and we are required to create some new salesforce fields that I am looking to see if anyone has found a good way to create them (possible with CPQ as well). The fields are:

• Original Contract Date  Must be a date field type. This identifies the date a customer signed on.
  
• Current Contract Start Date  Must be a date field type.
  
• Current Contract End Date  Must be a date field type.

As well, we have some salesforce accounts that have multiple active contracts, so I am not sure what might be the best way to solve for that. 



I have tried to build a rollup summary field but I can only use a number field type for that.



Any advice would be greatly appreciated.



Thanks!