[Serusers] SER and SIP headers

Hello I would like to ask the list some questions about headers. I've been reading the list and textops module, but I haven't found how to do this. Imagine a scenario with 2 SER proxies. The first proxy adds a header like: Path: <....> 1 )How can the second proxy add a parameter to this header (and not a new header)? The result that I'm looking for is something like: Path: <....>,<....> 2 ) I know that SER can check whether a header is present(is_present_hf()), but is it possible to extract the information of a header and use it? I can't use search() function, because I don't know the information, just the header name. I need to read some parameters from a header of a SIP message to construct a new header. Thank you very much for your time Regards, Curro