How to use column in sales order form as display field?

Hello,

if there is a requirment to display additional info like qty available in sales order line form.

how can i do this ?

I am asking about where is the place that i can display my data?

can i use any column that i don't need in sales order form as display field?

if yes

how can i know that this column will not cause problems in the future and this column is not populated at any event ?

Note that i don't prefer to use flex field because it is very hard for the usee to navigate to the end of the line for each row especially the numbers of line is large