Differing time signatures across staves.

I am engraving a new piece, written in a rather archaic style, with some archaic notation. Namely:

The piece is in 3/4. At one point, some – not all – parts start moving in triplets, i.e. 9 notes to the bar.

However: the composer chose to write these parts in 9/8 time, as opposed to triplets.

I would like to keep this feature in the engraved score and parts; of course one wants to stay as true as possible to the composer’s intentions.

So: is there a way to write some parts in 9/8, and some parts in 3/4 … where the dotted quarter note of the 9/8 equals the quarter note of the 3/4?!

Sounds impossible.

It is however a feature not unheard of in older music. Maybe one day?

See this thread.

Thank you. I hope my freak example can be added to the list of features to be considered.