Block Deletion of attachments

Hi

Is there any possibility to block deletion of an attachement in a rich text field ?

I read many about attachementd in Lotus but can`t find anything about it. I have an Excell attachements in a database that I want the users can read, edit but not delete, is there any way to secure them in a field against deletion ?

The second question:

I have database with many excell attachements placed inside a separate Lotus documents in a rich text fields, is there any possibility to make a run excell formulas between them ?

ALl Excell attachements are in the same Lotus database, but in other documents, I want to create another one excell attachemnt where the sum of some fields from others will be calculated, is it possible in Lotus 8 ?