Hi:
All the appending that you do with ODS HTML happens at the end of the file not at a place that you choose. You can't really "prepend" a file at the "top". One thing you might consider doing --would be to save the PROC COMPARE output to an ODS DOCUMENT store and then to do your PROC PRINT followed by a PROC DOCUMENT replay for the PROC COMPARE output objects.
I have used PROC DOCUMENT and ODS DOCUMENT for storing and replaying output objects, but not with PROC COMPARE. Although, this paper shows using PROC COMPARE with ODS DOCUMENT:
http://www.nesug.org/proceedings/nesug07/ap/ap15.pdf
So that is one avenue to try. If you prefer not to work with ODS DOCUMENT and PROC DOCUMENT, the only thing I can think of is to create your HTML file with PROC COMPARE, then create a separate HTML file for the PROC PRINT and then write a DATA Step program to post-process the first file and to insert the second file wherever you want.
cynthia