Tab to get sub section numbering in word

Help
1

I have to insert text at proper place in word with proper numbering. I am able to insert at proper place. Regarding numbering, using paragraph break, i am able to get next section numbering. But since it is the child section or sub-section, using tab character I wanted to get the sub section numbering. But it is not working.

Eg.
What is happening
2.2.1 In Scope
2.2.2 [some scope requirements]

What I want
2.2.1 In Scope
{tab } 2.2.1.1 [some scope requirements]

vbTab or chr(9) introduces tab space but it does not introduces the sub-section numbering.

Eg.
What is happening with vbTab or chr(9)
2.2.1 In Scope
2.2.2 {tab} [some requirements]

What is expected(section number to be changed)
2.2.1 In Scope
{tab} 2.2.1.1 [some requirements]