Need custom data entry fields

Every booking whether direct or OTA should have a “Notes” section and there should be the ability to have some custom fields (conditional field data) for additional data that could be crucial for the host. For example, when early check in is available, we select “Yes” and the system will either send a message to the guest notifying them OR it can add this comment to the check in instruction that early check in is available. It is a simple conditional database that can be integrated with IGMS. The fields can be character, yes/no, or numerical. This can help a great deal with accounting as well. Currently I have to keep a spreadsheet with this extra data relating to every booking. Thanks