Password protect a mailmerged document ?

[KiaruB]

Hello,

Our company makes hundreds of price offers every day.
At the moment we make an offer in Word with mailmerge.
After the doc is created we make a .pdf of it to make it the client a bit more difficult to change anything.

We wanna cut out the .pdf making because it's eating alot of time.

I found some password protection code to put in a Word document so it reacts the same as a .pdf

but...
the code is in the Word template
when processing the template thru mailmerge the code is
gone...protection gone...

any advise on this one ?

thanks.