Modification of one character in a font file

Hi, I’m a graphic designer who often been asked by clients to do small modifications in their CI fonts. As far as I know, it’s not really allowed to do that, but I guess many designers and typography do it. Of course, we bought the fonts officially and they are licensed for the customer.

Currently, I have a client who doesn’t like the DIN Next @-character. So I was asked to make it more round. My question is now, what do you think generally about the task and can somebody explain, if there are any special settings or export options which you would set in Glyphs in such case?

I have basic Glyphs-skills and can exchange one character path with a new vector path. But I don’t know which font information should I modify and even which settings are important in the export dialogue.

It’s not the aim to me, that I want to crack an official font file to bypass costs or have selling ideas. I think its a common design task which comes up from time to modify or expand a certain font, which was bought by a client.

Would appreciate your thoughts about it.

Cheers, Alex