Then and Therewith

Then adverb - In addition to what has been said.

Therewith and then are semantically related in purpose topic. In some cases you can use "Therewith" instead an adverb "Then", when it comes to topics like event, at that time.

Therewith adverb - With that or this or it.

Then and therewith are semantically related in purpose topic. You can use "Then" instead an adverb "Therewith", if it concerns topics such as event, at that time.