Hi Aiden,
Welcome to the forum.
To add the initial chord sequence into Scaler you need to use the DETECT function
Then just drag your clip onto the middle of Scaler (note you can detect either midi or audio clips). Scaler will open a dialogue confirming you want to replace the existing sequence in Section A with your new clip.
Click on “YES” and your new clip will appear in Section A (note this does not affect any chords you have in Section C). Scaler will also display a selection of suggested scales for your detected clip, the topmost being the most likely scale.
If you then select a scale from the suggested list of scales you could try using the SUGGEST dialogue in Section B to create sequences for the chorus, bridge, or even a different verse.
For the sequence in my example I have chosen the E Locrian scale from Scaler’s suggestions
If I now click on the suggest button Scaler
will suggest a series of chords from which I can pick a chord for the first block
Note that these are chords that scaler’s algorithm suggests may fit the selected scale. They are not necessarily from your chosen scale. But by clicking on the TONAL button
I can select PER SCALE and get diatonic chords from my chosen scale.
Note that every time you click on the SUGGEST button you may get a new sequence of chords.
I can now drag these into my pattern.
Another approach may be to use some chords (say the first two) from your pattern by dragging them into Section C and then using the SUGGEST function.
Finally if you want to keep the harmonic structure of your chords, but just change one or two to an extension (7th, 9th, sus2 etc.) you can do this either on the MAIN page or the CHORDS page, which will give you a greater selection of variations (see links below).
Secondary dominants may be found on the MOD page
Here are some tutorials that may helps you:
Introduction to CHORD Variations
Searching for Chord Variations and Extensions
The Chord Page: Inversions
Finding Secondary Dominants
Also check out the on-line Scaler course on School of Synthesis
Hope this helps