Almost every small fish will eat fish eggs and/or fry. Normally if it's alive, wiggling, or recognized as food and it fits in the mouth of any fish, it will get eaten.
As far as I know there aren't many or any shad type options for fish in Missouri except the threadfin or gizzard which are not well suited for this application. The other hurdle is locating the 'stocker' species for sale. If you are really serious about benefiting the crappie(blk/wht) population once it is established then consider annually evaluating the pond's shiner and crappie population and when needed supplement the shiner numbers by adding the GSH fry package from some minnow farm such as:
http://www.andersonminnows.com/GoldenShinerFry.phpYou can buy them or raise your own in a separate forage pond. Release the new forage in the shallowest best minnow type habitat available in the receiving pond; often this is a wetland type area. If you are interested in collecting native fish that could be candidates as forage species see this book or one similar to it.
https://www.amazon.com/Fishes-Missouri-William-L-Pflieger/dp/1887247114 https://www.amazon.com/Fishes-Arkansas-H...f61-402d-11e9-bThe idea of building the forage pond with a drain at higher elevation is a very good plan so draining the forage pond water into the main pond is the easiest and simplest way to harvest or utilize the forage fish. Several forum members have used this excellent pond management option to supplement forage fish.
For best success for crappie, one of the main things you will have to do is learn how to best annually assess or evaluate the 'health', numbers, or density of both the shiners/forage community and crappie population. For the crappie this will be determining the general body condition(RW) and status of each size class.
