I agree with those that find little or no relevance to NGDF. And it's a terrible list. The only part that's reasonable accurate is the UP part, as UP is actually the one surviving RR that absorbed the listed components, but DRGW disappeared into SP well before SP into UP. And as Hank stated, including predecessors is problematic at best, because there have been so many breakups/mixing of former properties and those properties were also often made up of even more 'Fallen Flags'. And with Conrail predecessors, why don't you have Conrail and the predecessors also under CSX? Par example, my home district was the Southern Tier Line and it's environs, comprised of EL (DLW & ERIE
predecessors), LV, PRR, and NYC which all did go to NS, but the Tier was part of the Albany Division, who's high tonnage main line was the NYC (and West Shore) from north Jersey to Fairview, PA (CP-97) and became a very important part of CSX in 1999. BNSF did not
merge with BN and ATSF - BN was made up of all the rest of what you listed there (except ATSF) and BN and ATSF
merged to become BNSF. Same with the CSX primaries - Seaboard and Chessie were made up of the other predecessors and
merged to become CSX. There was no BNSF or CSX to merge with anything before the primary systems merged and created them.
RR merger and business history is far too complicated to put in a simple list like this. I suggest, after doing a LOT more studying, that a better format would be a family tree style chart for each current system, which would have to be broken down further into trees for many of the predecessors. But please leave NGDF out of it unless you get directly into NGs. By the time any of these modern (last 60 years) mergers happened, the DRGW and C&S narrow gauges were small, unwanted remnants of standard gauge systems. Also don't forget things like how the C&S ng would flow into BN/BNSF but was also at one time part of UP. And there are other NG outfits that were standard gauged and absorbed by larger RRs that you'd need to include to make it truly relevant to NGDF. There are already a whole lot of books out there already on the histories of the slim gauges you're trying to make reference to, so good luck tapping that market.