Altered feed-item nodes not refreshing requirement?

Hi,
Is it possible to keep some feed-item-nodes not refreshed while reffreshing a complete feed?
I have the requirement that I get feeds in with lots of feed-items. This is working great.
But I want also to alter some body fields of feed-item-nodes with my own content. These altered feed-item-nodes should not be refreshed with new information. The not altered feed-item-nodes need to be refreshed. Is this possible?

Greetings,
Martijn