Chord Tool Question

I’m trying to be more comfortable with using Dorico while I am fully switching. One of the things I do is that I make Hymn-scores. The way I have always done it is that the top two parts and the bottom two are notated as chords, except for if rhythmic durations occur.
The way I input the notes, however, is that I input the soprano line, and then the bass line, then I fill in with Alto and Tenor. However, when I input Alto and Tenor line, I find the chord tool makes it harder to input those lines as chords. With Finale, I could just hit a number key, and then a chord note of exact duration would happen, but with Dorico and the chord tool, I find, I have to make sure the exact rhythm is selected in order for the note to input properly as a chord, or else weird chord durations will start to appear.
I was wondering if there was an easier way to produce results, like maybe if there was a way to notate on separate voices, and then merge them into the same voice to appear as chords.
Is there?

Far quicker to select the note and use the Shift-I popover and type -M3 for a major 3rd below etc.
If you have a line in thirds (or whatever) you can select multiple notes.

The behaviour you describe with the note durations getting changed unexpectedly when you change the duration after adding notes to existing chords is something we plan to fix.

In the meantime, though, I would indeed suggest entering your alto and tenor parts in separate voices, then merging them together. Select the notes that are in rhythmic unison, then do Edit > Voices > Change Voice, and choose the appropriate existing voice as the destination.

I also found that Lock Duration used with a MIDI keyboard allowed me to replace single notes with chords in the existing rhythm where I wanted.