Variables or placeholders in sitemap

I have many many sitemaps but they are very similar. Mostly change is only a word in a url or a different argument.
So sitemap list is very long but the sitemaps are very similar.
It would be very good and save a lot of time if we could use placeholders/variables in sitemap that I can fill manually before scraping starts.
So for example I have regular sitemap url like: http://www.test.com/&arg1=123&arg2=456
With variable I could make sitemap url like: http://www.test.com/&arg1=##input1&arg2=##input2
Now when scraping starts when it is asking me to enter request interval and page load delay it could additionally ask me to enter value for ##input1 and ##input2.
This would help to reduce number of sitemaps I must make for all different arguments.