How you proceed with setting up will greatly depend on how you would like to work. Here are some things to consider before starting...

_ The MONTAGE has 32 audio bus outputs - do you plan on taking advantage of this capability when recording?
_ Are you planning on playing and singing simultaneously (meaning do you need the Mic and Synth for simultaneous recording)?
_ Are you okay with recording music tracks first, then adding mic’d audio tracks as overdubs?
_ Do you have a computer? — the Type will determine what options you have when configuring your system. And will determine the version of the Yamaha Steinberg USB Driver that you’ll need.
_ Do you have Studio Monitors?
_ Do you have a separate Control Room and Studio? (In other words, are your Studio Monitors in the same room with your microphone? (A typical home studio arrangement). If yes, you will need a way to turn the speakers OFF when using the Microphone.
_ Do you have a quality set of Headphones for overdubbing via the microphone?

There is no one single way to setup a system. The fact that you may need to configure things one way for working with your synth, and another for overdubbing with the microphone is a possibility. More gear may also be a possibility....

Let us know.

Thank you Bad Mister. I appreciate your assistance.

The MONTAGE has 32 audio bus outputs - do you plan on taking advantage of this capability when recording? - Yes.
_ Are you planning on playing and singing simultaneously (meaning do you need the Mic and Synth for simultaneous recording)? - Yes
_ Are you okay with recording music tracks first, then adding mic’d audio tracks as overdubs? - Yes but typically I would record various midi instrument tracks via montage. So when I sing, I need montage for the instruments unless I convert the midi to audio before singing which I do not so at the moment.
_ Do you have a computer? — the Type will determine what options you have when configuring your system. And will determine the version of the Yamaha Steinberg USB Driver that you’ll need. Yes - Windows 10.
_ Do you have Studio Monitors? - Not at the moment.
_ Do you have a separate Control Room and Studio? (In other words, are your Studio Monitors in the same room with your microphone? (A typical home studio arrangement). If yes, you will need a way to turn the speakers OFF when using the Microphone. - No.
_ Do you have a quality set of Headphones for overdubbing via the microphone? - Yes.

Ok, so I think I have resolved the issue. The biggest problem was dealing with what I do not know which becomes this black hole of endless unknown. Anyway, to get my Montage and UR12 or essentially my Condenser Mic to work nicely together I had to edit the performance on the Montage and under:
Audio In --> Mixing ----->A/D In:
----->Set "Input Mode" to "L Mono"
----->Set "Output Select" to "USB29&30"

Then in Cubase under Studio --> Audio Connections -->Inputs, I added another Stereo Bus and assigned the Left and Right to USB29 and USB30 respectively. This ensured I did not record the midi instrument's output as audio into the audio track I used to record my singing via the mic. I am sure this is not 100% correct but it works 😉

Are you using a stereo A/D output because you use stereo insertion effects? That's fine. Just wondering. Without insertion effects, you could reduce down the configuration to a single USB channel.

https://www.yamahasynth.com/learn/montage/setting-up-the-a-d-input-montage

Are you using a stereo A/D output because you use stereo insertion effects? That's fine. Just wondering. Without insertion effects, you could reduce down the configuration to a single USB channel.

Thanks Jason. Good point. To be honest, I just got it working that way and was not using any insertion effects. However, after reading the link you provided from Bad Mister's article, I am going to experiment a bit to see what it can do. Why did I not start with this 20 years ago? So much to learn and understand let alone master!

https://www.yamahasynth.com/learn/montage/setting-up-the-a-d-input-montage

Montage and MODX are both instruments from the "deep" section of the Yamaha synth pool. They are both very flexible in configuration, sound sculpting, behavior response, etc. Therefore both of these models have volumes of options to master in order to reach every corner of the instrument's capabilities. This flexibility would be part of the reason to get a Montage/MODX over the instruments that are not as deep - that you need or want the ability to adjust the instrument to fit your liking. As in any endeavor, when there are lots of options - there is also the burden of understanding the options in order to best make the choices that lead to success. Although improvements can always be made - this generation is more accessible than ever before on the ease-of-use scale. There are a few head scratchers - but the forum and associated content (tutorials, videos, etc) is/are here to help sort those out.

Montage and MODX are both instruments from the "deep" section of the Yamaha synth pool. They are both very flexible in configuration, sound sculpting, behavior response, etc. Therefore both of these models have volumes of options to master in order to reach every corner of the instrument's capabilities. This flexibility would be part of the reason to get a Montage/MODX over the instruments that are not as deep - that you need or want the ability to adjust the instrument to fit your liking. As in any endeavor, when there are lots of options - there is also the burden of understanding the options in order to best make the choices that lead to success. Although improvements can always be made - this generation is more accessible than ever before on the ease-of-use scale. There are a few head scratchers - but the forum and associated content (tutorials, videos, etc) is/are here to help sort those out.

That is exactly why I made the investment into this fantastic synth. I did not want to end up with an instrument that could only go so far. The challenge is to challenge oneself to continue pushing one's own boundaries and discovering all relevant aspects it has to offer. A great thank you to people like yourself, Bad Mister and all other contributors who take the time to assist and share their knowledge!