Wireshark merging files advice

[Davit2005]

I have to quite often packet capture files but I'm struggling to achieve a way (unless I am missing something) of identifying capture files once merged i.e. we get a packet capture from our firewall and the 3rd parties firewall. I've tried adding hardware i.e. MAC address. Even putting the file name in a column would help before merge if I could do that.

 

Anyone?