In case anyone is interested, you can order frozen dumplings from Dumpling House in Temple City. You need to order at least 50 dumplings. The cash price is 20% of the regular price, so it'll be about $23 for fish dumplings and $19 for boiled-type pork dumplings. You need to order in advance (one week for us). The good thing about this is that you can specialize your order. For example, we ordered dumplings without MSG and half the salt they would normally use.
The owner recommended boiling the dumplings. Customers have complained in the past that the steamed dumplings fell apart. He's not sure why, though, but there have been no problems with the boiled dumplings. Here's the contact info:
5612 Rosemead Blvd.