One Time Pad for large changing files i wondered what the security implications are if I do the following. If I had a large file encrypted with a OTP and want to change only a few bytes in the plaintext. what security vulnerabilities do I get if I only generate a new OTP for the changing bytes leave the old OTP as is and substitute the new OTP, and do this every time i make a change to the plaintext.

To be clear: 


plaintext p; 
OTP o; 
cyphertext c  


Start with…

p = 1111 1111 1111 1111  
o = 0001 0001 0001 0001  
c = 1110 1110 1110 1110  


change plaintext…

p = 1111 1111 1111 __1010__


generate new OTP for the last 4 bit 0101 und substitute it in the "old" OTP…

o = 0001 0001 0001 __0101__  
c = 1110 1110 1110 1111 


What are the problems ( if there are any ) resulting from this? 

I know that if I want to use OTP, I have to generate a hole new pad. But if I have a huge file (multiple GBs), it is hard to generate a new pad of this size if I only want to change a few bytes. 

I haven't found material about this topic so far and analyzing attacks against some cypher application is a hard task, but maybe someone has read an article about that OTP application and why you should not do this.
If you only ever use a particular OTP block to encrypt one plaintext block, there is no way to decrypt it.

However, with your approach anyone looking at multiple versions of the file will be able to tell which parts have changed. For example, if the file contained secret messages stored by users, it would leak the length of each message added. Maybe that's a problem, maybe not. Depends on your application.