Have you read the last paragraph of my answer you are linking to in your question
as well as my answer in the whole dwelling around Infopath form template of type/compatibility Sharepoint List Form hinting on its peculiarities discussed many times before?
You shouldn't use Infopath form template of type/compatibility Sharepoint List Form for this as it has locked
- locked through unmodifiable data connection/source created under the hood when you created such type of form.
Sharepoint List Form is created either by pressing Customize button on ribbon of browser or in Sharepoint Designer or choosing File > New > Sharepoint List > then following to fill "the locking" data connection wizard in Infopath Designer 2010 (IPD)
Please check this inmodifiable data connection/sourcу by having clicked on ribbon Data > Data Connections of IPD
data schema to its sharepoint list, i.e. rigidly bound in one-to-one relationships between Infopath form template data and its sharepoint list
Since you insist on asking the same again I have to ask you:
how do you imagine where how another table, with another schema, would store list items (with a different data schema) in the same sharepoint list (items)?
If you choose to use Sharpoint List Form:
- it is your choice and you should understand what you are doing and what this type of form is by its design for.
Such type of Infopath form template, Sharepoint List Form, is designed to store items of one and only one sharepoint list (according according to data schema of one and only one sharepoint list) but not multiple ones
- Sharepoint list is inherently flat, it data schema cannot be hierarchical
You should minimally read on (usage&design) differences between sharepoint list vs. sharepoint library: