Crystal Report Sorting Groups (1, 1.1, 1.1.1, 1.2, 1.2.1,, 2, 2.1, etc.) and sub-totals per group?

In my report used for quotes and invoices I've got two groups: main voucher-postion number and sub-groups of the main position.

I'd like to achive this kind of sorting with sub-totals:

1

1.1

1.1.1

1.1.2

• Sub-total of sub-group 1.1. (running total for 1.1.1 to 1.1.x)
• Sub-total of main group 1 (running total for all positions grouped in 1)

2.

2.1

...

• Sub-total of sub-group 2.1. (running total for 2.1.1 to 2.1.x)
• Sub-total of main group 2 (running total for all positions grouped in 2)

10

10.1

10.1.1

• Sub-total of sub-group 10.1.
• Sub-total of main group 10

etc.

From this post I got most of it to work: https://answers.sap.com/questions/8017433/crystal-report-record-sorting---numerical.html (many thanks to the cotributers! :)

But, in my current report is showing e.g.:

1.

1.1

1.1.1

10.1

11.1

2.

2.1

etc.

Any ideas how to get the sub-groups aligned with the main voucher-positions for anything >9?