Validation on a question block containing a link to different survey.

It is possible, but complicated. You can use the save & continue feature of Qualtrics to go to another survey then come back to the same place. You'll need to use ajax to check the respondent's survey 2 status. If survey 2 isn't complete replace the Next button with a fake next button that redirects to survey 2. Send the survey 1 url to survey 2 so survey 2 can redirect back to survey 1.

https://community.qualtrics.com/XMcommunity/discussion/comment/47707#Comment_47707Hi Tom, thanks for your response. Currently, we are facing a few more challenges regarding the same. First, the link for survey 2 is created by using specific embedded data from survey 1 and the anonymous distribution link of Survey 2. We are unsure if the above method applies to the same because the anonymous link is reusable, and currently, we do not have any technique so that respondents can use it only once.
Additionally, do you have any suggestions on where we can leverage this code of Ajax and implement it? Thanks for the help

https://community.qualtrics.com/XMcommunity/discussion/comment/47709#Comment_47709If you do as I describe you don't need to worry about them taking survey 2 multiple times. When they get to the appropriate place in survey 1 they will click Next (fake Next) and go to survey 2. When they complete survey 2 they will come back to the same place in survey 1 and the script will automatically click the Next button to continue with survey 1.
As for ajax, start here.
As I said previously, it is complicated. Normally, you would only do this if you needed to go to a different platform for survey 2. If survey 2 is a Qualtrics survey, which seems to be the case, you are probably be better off making it one survey.