Adding extra mark on a word

Hi,

I am designing some strange font that required to make a line from one letter (character) to the end of that word.

For example, if my text is “Hello big World” and my signalling letter is “l”, the letter o in “Hello” will have a line on top of it and “d” in “World” will have the same line.

I am new to the software and thank you for help in advance.

There are some forum posts with similar questions. Do search for contextual substitutions.

Thank you for your replay.

Can you suggest something or a keyword, please?

Your project seems odd to me on the surface.
As Ewrin suggested, searching for “contextual substitutions” migh give you some ideas . . .
https://forum.high-logic.com/search.php?keywords=contextual+substitutions&terms=all&author=&fid[]=3&sc=1&sf=all&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search