When I have 300 reservations I try to find names and share with the temple but I am stopped it will not let me find and share. What can be done
Move 200 of your reservations to your Shared With Temple list. Then you will have plenty of room to find and share more names.
If your personal list is full of names that say "Ordinances that were previously shared with the temple cannot be shared again," that means you have taken a bunch of 90-ordinances that were already shared with the temple. if you cannot complete all of those ordinances within the next 90 days, then you should release them back to the temple list so that others can complete them. The step to do this says "unreserve," but you are not really unreserving them. You are putting them back on the general temple reservation list.