Have gnome & plasma at the same time?

I’d like to have both gnome & plasma usable at the same time (some users might prefer one or the other). But enabling both of them via:

services.xserver.deskopManager.plasma5.enable = true;
services.xserver.deskopManager.gnome.enable = true;

would give some conflicts of configuration, like programs.ssh.askPassword etc. So what is the clean way to install both of them at the same time? Should I manually fix all conflicts? What if some conflicts are kind of impossible (gnome really needs config A, plasma really needs config B)?

I fixed it a while ago by including this in my config, i forgot where i initially got it but it seems to works

ssh.askPassword = pkgs.lib.mkForce "${pkgs.gnome.seahorse.out}/libexec/seahorse/ssh-askpass";

Thanks a lot! Since it seems a bit more invasive than the kde version, I finally chose the KDE one:

programs.ssh.askPassword = mkDefault "${pkgs.plasma5Packages.ksshaskpass.out}/bin/ksshaskpass";

I was just encountering the same problem…thanks for this post.