Not yet on our Roadmap/agenda.

2nd half of 2020 we will focus on widget improvement.

This might be a candidate but no promises yet.

@MathFour, you might want to check this post out where a custom widget is provided that can be placed in the Application Specific Resources:

https://community.aimms.com/aimms-webui-44/how-to-combine-bar-chart-and-line-chart-495 

It does miss a lot of the standard AIMMS properties such as store focus, tool tip, hover effects etc. and it does not fully align in style (as its not an AIMMS widget); but it might help give you a starting point.

This sprint we spiked a 1st version of the combined chart and I got a demo today of the team working on this. A first version will (at least) allow you to add 1 line identifier and a set of bar identifiers (stacked or grouped).

Still work in progress, but we are aiming for a 4.76 release (fyi: release 4.75 is expected next week). 

Now released in 4.76. See https://www.aimms.com/support/new-features/