PPRuNe Forums - Numbering headings in Word 2016

Back on PPruNe after a while and I have a question for any Word whizz kids:
For years I have been writing maintenance organisation and maintenance management manuals for EASA organisations. These are based on templates in the regulations and have some heading numbering that doesn't necessarily match with the default numbering and style formats in Word.
I have always managed to get the numbering to work after a fashion but just lately I've upped my game to learn how to create sections with unique page numbering and headings. However, one format I cannot get to work relates to the template for the Maintenance Organisation MOE. The model I use has five sections and I have had few problems numbering headings, sub-headings and lists such a Part 0 with headings configured as 0.1, 0.2 etc and sub-headings such as 0.1.1, 0.2.1 and following sections such as part 1, 2, 3, 4, 5 with headings like 1.1, 1.2, 1.3 and sub-headings of 1.1.1, 1.2.1 down to level 3 and using modified headings in Styles to get it to work.
One format will not auto number or set consecutuve headings or sub-headings. That format starts with the letter L (L2.1 XXXX, L2.2 XXXX etc) and the sub-heading L2.1.1xxxx etc with the next heading and so on. No matter what I try in styles or numbering lists (and whatever I read online), I cannot get it to work in the manner of the successful ones mentioned above. I think the problem is the headings and sub-headings start with a letter (L) rather than a number.
Any ideas? To summarise. I need a section to be titled 'L2 Additional Line Maintenance Procedures' with following headings of 'L2.1 Additional Line Maintenance Procedures for Tooling' with a sub-heading 'L2.1.1 Tool Control' and a sub-sub-heading etc. Next heading will be 'L2.2' and so on. I want to tie the footer page numbers to the headiing number, too.
Help!