Field information transferred from Interaction to Incident

Guys,

Can someone guide me which is the best approach to achieve the following:

I've created a custom field add.info in ess.do form which is a dropdown menu with predefined values: lets say a list with values from 1 to 5.

The scenario:

The end user is opening the ess.do interface and is selecting Submit a Request. There except the out of the box fields there is additional field with dropdown menu add.info. The user fills all the necessary information and from add.info selects lets say 3.

Now the ticket can be opened from the operators from the index.do interface and start processing it. There the add.info field is added through the Form Designer in the SD.open.interaction and SD.update.interaction forms and the value selected from the end user is visible without any additional modifications.

However, sometimes the interaction will be escalated to an incident. And it that incident most of the information is also transferred automatically for the out-of-the-box fields. But since add.info is a new custom field it should be set somewhere in order this info to be trasmitted.

I've created the add.info field in the probsummary table and after that i've tried from link to add in probsummary, IM.open.incident and IM.update.incident the following:

Source fields Name: add.info

Target File Name: incidents

Target Field add.info

Apparently this is not right or at least not enough.

Can someone guide me what should i do in that situation?

Many thanks in advance.