Okay Taco, so that's a possibility I can explore, even though it is not 
a nice one, as you say. I can think of a couple of other not-so-nice 
ways of achieving a result as well. The manuscript shown me (in MSWord, 
obviously) has been carefully prepared to ensure no text flows over a 
page, so we are really dealing with separate pages. But of course, all 
that changes once page dimensions and font size etc. get involved at the 
ConTeXt stage.

However, you gave me a clue: 3 files: "by creating two separate pdfs for 
the page bodies only and using a third context doc to include those 
pages alternated'.

For the first chapter of the proposed book I have tried Wolfgang's 
suggestion as listed in https://wiki.contextgarden.net/Columns#Streams 
by simply using the \input method. Obviously 'en' and 'vn' stand for two 
tex files set up as I normally would with preamble and bodymatter. I 
certainly get a good result once the chapter starts. It would seem 
logical that further chapters can be added. Obviously I only want one 
TOC, not two (only call it in for, say, the en.tex but not for vn.tex) 
and for some reason I have several blank pages before everything 
starts... but hopefully can solve that. Maybe I can adapt what we have 
below with the project structure.

Not ready to give up yet!

Julian

\starttext

\startoutputstream[one]

\startcolor[red]

\input en\par

\stopcolor

\stopoutputstream

\startoutputstream[two]

\startcolor[blue]

\input vn\par

\stopcolor

\stopoutputstream

\synchronizestreams[one,two]

\setbox\scratchboxone\outputstreambox[one]

\setbox\scratchboxtwo\outputstreambox[two]

\doloop

{\ifvoid\scratchboxone

\exitloop

\else

\setbox\scratchboxfour\vsplit\scratchboxone to \textheight

\vbox to \vsize{\box\scratchboxfour\vss}%

\setbox\scratchboxfive\vsplit\scratchboxtwo to \textheight

\vbox to \vsize{\box\scratchboxfive\vss}%

\fi}

\stoptext

On 3/4/23 20:15, Taco Hoekwater wrote:
> Way, way back when, I did a document in NL + EN by creating two separate pdfs for the page bodies only and using a third context doc to included those pages alternated, with the correct headers added in that third document. Not a ’nice’ solution at all, but it worked for me. (this was in the nineties, though)