Thanks for all your replies. Here is what I have done so far.

1. PVG is a business trip and the invitee (our parent company) will pay for my ticket from LAX-PVG but the nature of our relationship precludes me bringing up my vacation. It is the way it is. The business trip is optional but beneficial to me.

2. I was unable to find the fre rules on Delta.com and do not have access to KVS or Expertflyer (apparently a moot point since Delta fare rules are not available there anymore).

3. I did try to reprice the tickets on Delta.com for one week ahead (and even 2 weeks ahead) and this is what I get.

Price per passenger
Old ticket price in new currency: $1,900.00 (USD)
New ticket price: $9,515.30 (USD)
Change fees: $450.00 (USD)
Balance due (including change fees): $8,065.30 (USD)
Total
Old ticket price in new currency: $3,800.00 (USD)
New ticket price: $19,030.60 (USD)
Change fees: $900.00 (USD)
Balance due (including change fees): $16,130.60 (USD)

Given all the options, barring a miraculous waiver from a Delta agent, the best situation seems to be to ask my employer to book my from PVG to HEL. But what do I do with my ticket? Will the agents at least convert my Roundtrip to a One way Return without charging me thousands of dollars?