I have a word document currently used in a mail merge. My product owner wants it setup to use SSRS so we can take advantage of internally generated data in addition to the stock data our vendor's platform provides. The platform integrates with SSRS so options that are not SSRS are not available to me. I found this question but it's been inactive for 9 years and didn't get a lot of traffic and the linked blog post appears to be gone.
Using a Word document as a template for an SSRS report?
Is there any way to use the word doc as a template, or some kind of starting point in SSRS?
Unfortunately this is not possible without a lot of work. I had the same issue several years ago and ended up writing an application in C# to do all the work. This was not something that we could achieve in a few days.
Just in case you considered going that route, here are some of the issues you might face and what we did to get round them.
The basic principle was to get SSRS to dump out a word file then our app would read thru it and extract the content, pasting it into a new document which was based on our Word Template.
If I had to repeat the process avoid doing what I did and I would concentrate on getting SSRS to output exactly what was required, matching the template design but this is only good if you don't have things like form fields etc as SSRS cannot produce these.
Word Automation is another option but that is slow or maybe look at some of the Apose renderers and see if they are of any use. ( https://www.aspose.com/ )
Sorry its not the answer you wanted but hopefully it will save you some time trying to figure it out.