FRACAS: linking data between subtables. Is it real?

Our customer used all of FRACAS user-defined fields and it's necessary to describe some FRACAS workflow and we decided to use FRACAS Subtables to resolve that problem (and they are logically suitable for describing customer's workflow). In customer's case data must be linked between FRACAS subtables.

How can we copy (or have access to) the fields between subtables?

For example:

We have 3 incidents subtables (0-1.png, 0-2.png, 0-3.png)

The goals is:

1. Copy fields value from Subtable 1 to Subtable 2
2. Display fields from Subtable 2 and Subtable 3 in Subtable 1 form

What we try to do:

1. We try to create user-defined calculation of text type (return field is User Yes/No) and in calculation window to assign values from Subtable 2 fields to corresponding fields from Subtable 1. We had a warning window when we verified that calculation (maybe due to incorrect syntax?) - 1-0.png. If we make this calculation we can add button to run it - 1-1.png
2. In the form editing mode we couldn't find any functionality to add fields from any other subtables - 2.png.

How can we reach our goals?