Not as I've offered. The items that appear in the Share Menu originate from Extensions built directly into an application's "PlugIns" folder, sometimes called "add-ons". Mail is very extensible and many companies offer free and commercial plug-ins (
https://www.lifewire.com/popular-mac-mail-add-ons-1172708) - plug-ins for Mail can make Mail a completely different beast, just like MS does with the Outlook app and its add-ins.
The OS and some of its apps are far more intertwined than one would think at first glance. I use Windows every day, I'm an engineer, civil construction is my main bread and butter and I run a Win 10 Pro VM on my Mac so I've got some of my work with me any time I need it. But, I find OS X is as powerful as Windows, relevant to enabling a user like ourselves that are willing to explore the tools/apps supplied by great developers. Most Mac apps ship with built-in extensions, with commands and ties available in the Services Menu - System and app Services appear when data is to be transmitted - to the Clipboard (another very powerful tool in the right hands and with some forethought) and on to another app or destination. For instance -
highlight this text and leave it highlighted - then, click on your browser's app Menu (e.g., Safari or Chrome), click on the Services Menu and you'll see "New Email With Selection" - click on that Service Command and you'll get a new email with the text formatted exactly as it's set up in this post.
Alternately, go back to that Services Menu and click on Services Preferences, and you'll likely see dozens of available Services from the apps on your Mac. Additionally, you can enable/disable them through the adjacent checkbox. You can also add a keyboard shortcut or remove/change the shortcut just by clicking in a data field just to the left of that checkbox (it's not visible, but it's there…).
There are options for customizing your workflow, more so than most Mac users are aware of. In the Keyboard>Shortcuts System Preferences Pane, you can really tweak your interface and workflow. For instance - I'm going somewhere with this - in the Shortcuts>App Shortcuts section, using the "+" button, I added a shortcut for "All Applications" and typed in "Zoom" and added the shortcut "Control-Z" by holding down those two keys. Now, I can Zoom an application Window just by holding down those two keys (except for a few apps, like MS Office apps that use "Zoom Window" instead - but I added one for Word and Excel in the same fashion). No more hunting for the mouse and navigating for that Menu Command or Option-Clicking on the Green Widget.
Here's "somewhere" now - for my Automator Applications, I added them to that Preference Pane and created a custom Keyboard Shortcut so I can launch it just by holding down those keys. Again, no fumbling with the mouse.
As to your specific need, AFAIK, and it's over my head here, you'd likely need to either luck out and find something on the web to fit your needs, learn how to build a custom Mail extension (extensions are located within the app's PlugIns folder, which is inside the app bundle), or live with the built-in Mail Service "New Email with Selection" and then address your new email message(s).
One more option in Automator - you can also create your own Services, and you can also add Keyboard Shortcuts to them, including the "New Email With Selection" option. I've typed enough for now, my SO is on her way! here's a few links to get your started:
http://www.macworld.com/article/1163996/software-utilities/how-to-use-services-in-mac-os-x.html
http://www.makeuseof.com/tag/add-useful-options-mac-os-x-services-menu/
https://www.howtogeek.com/205686/use-your-mac’s-services-menu-to-perform-quick-actions/
http://www.macworld.com/article/1164704/four_great_os_x_services_you_dont_know_about.html
Cheers!