So, I am making this post in continuation of the post I made earlier here (screenshot attached)...One Mod helped me, but I was upset because same information I read on NIOS website, and was thinking I have to go through all this Hustle to get my marksheet because I was a different case...
**Situation = Already passed NIOS in April 2025 public exam with PCM English + Data entry...
But Thought of giving NEET 26 so appeared for additional subject exam for Bio only in OCT 2025 public exam, but as I have already received My marksheet and other certificate from April 2025, so was confused how to get new 6 subject marksheet. Read on internet and got suggestions here in post to Visit Regional centre (it's far in my case)or study centre for it, and have to give my old 5 subjects marksheet to them first, but today without doing any of these got 6 subject fresh marksheet cum certificate today by Post at home  in which it is written (Appeared for improvement/ additional subjects.)... So now I get it why I was not eligible on NIOS portal to order this marksheet (it was saying to me you are NOT ELIGIBLE to perform this action) because it was on the way... I am making this post, so if in future anyone needs this information they know what happens,because I didn't find anything similar to my situation, and was extremely worried because in councelling I need these original documents.
..Also Thanks to Woodpecker Ji for always replying on posts when someone needs 🙏 ..

UPDATE cum INFORMATION!