I have merged in Subversion/TortoiseSVN like this a few times:
Method A:
1) I change the trunk and commit.
2) I make other changes in a
Regarding Merge range of revisions versus Reintegrate a branch:
Following Method B results in having two kinds of commits in branch:
When merging back to trunk, you must pick only changes unique to branch. This is done by Reintegrate a branch.
Using Merge range of revisions at the end would bring to trunk a mix of both duplicated trunk changes and private branch changes.