Well this is a copypasted guide from a user name neiser, i will give him all the credits and here is a link to his original post Install legacy drivers with supported drivers( my case 8650g(legacy)+8750mNo(supported)) [I put some notes for clarifications]
My notes are between []
[This work with Intel + amd graphics]
[I have hd 7620g with a series apu r7 m260 and it worked for me]
1- Download both drivers ( legacy and supported)
[Legacy would be 16.2.1 beta, and the supported it worked for me the 18.8.1]
2- With the utility amdclean up delete all the stuff realtionate with AMD
3- Reboot
4- Install the newest drivers but ATTENTION, choose the custom installation, don't mark the option of Radeon settings( if we want to access to it whe need to install the legacy panel control)
5- Without reboot, unpack your legacy drivers. Don't install it. [you can use .7zip to extract the files of the .exe, into a folder]
6- Right click on windows button, go to devices, then select your legacy product and click in update with local files( select where you unpack the drivers, most of times they are in C/AMD)
[If the device manager doesnt let you install because it says that the pc has determined that you have all ready the latest drivers, try again the same steps but this time enter to use a disk it will open a menu then search your legacy driver files, and it Will ask you to select a .inf file, this file Will in the folder,the file has a bunch of numbers and it start C0XXXXXX.inf most of the time it will start with C0 in my case the file is in
C:\Users\pc name\Downloads\non-whql-win10-64bit-radeon-software-crimson-relive-16.2.1-sep20\Packages\Drivers\Display\WT6A_INF
7- After the installation, not reboot, go to the legacy drivers, run them and when it ask what install, click on Radeon Settings.
8-Now reboot
9-Finally enjoy your gpu with the last drivers!!!!
Also radeon additional settings should crash, don't worry about it
I hope that this post become famous, if Amd could see this and includes the legacy drivers inside the radeon drivers would be awesome.
Curiosity: If i run the installation of Radeon drivers and then install Radeon Settings i get the new version, but after a reboot i am not able to open anymore radeon settings
. I saw the original post but you made it easier to understand and implement. Thanks 
