I need to achieve the following and not sure of best way. Large document that needs to be able to be referenced by paragraph as may be 100s of paragraphs. First col will be about 3.5cm<> 0.5cm space<>10cm main column or whatever figures work out on letter size paper. Adjustments made once I know what I'm doing.

1st col will hold a paragraph number on right of the column
2nd Col will have all the body text
1st column needs to have some width to it as I want to be able to put a basic note of what is to the right of it in main column. For instance, if this was about the UK and Brexit, the main right column will have essay type flow while the left column may simply highlight Mandate 12; European Parliament session July 20. All bogus stuff that but hope it helps show the idea of what I'm trying to do.

This runs continuously through document

The right column should be the only column accepting type unless I specifically change to the left column for a paragraph or section number or a 'highlighted note' and I don't mean a colorised note but just a marker or signpost for reader.

I hope this makes sense. It is for a complex argument and needs to be understood and referenced easily by a tribunal. Could be 60 pages or so in a continuous fashion with no real change in page construction throughout.

Many thanks.