If you are talking about the stamp, seal and signature required on the ANNEXURE-1 then you can take the same from your second school.
If you are talking about the documents (certificates of the requirements) to be submitted for application for conversion, then i would suggest you to take them from both the schools. That is, whatever flying you have done from your first school you need to take some documents from them. And also make documents from your second school for whatever flying you have done there.
If your first school if out of business and/or there is no possibility that you can obtain documents from them, ask your second school's chief if s/he would sign those documents for you. In short, try to get documents signed from your old school as well as your new/last school, for whatever DGCA requirements you have achieved flying with them, respectively.