Broadleaf Commerce Discussion Forums

Hi, I'm trying to add a text field to the shipping details form, I thought it could be done by extending Order entity, but then i found that Order entity has PersonalMessage field which is not being filled by customer during checkout process, so is it an option to use this field for my new text field, or is this field used for something else?

Yes, you should use this field. It is intended to be used in the exact way that you are describing, specifically on FulfillmentGroup.