Selectively including from a module - is this possible?

I have a collection of Mixins (you can call them “features”), organized
as a module:

module RM
module Mix; def foo; puts 555; end; end
module Mux; def bar; puts 666; end; end
end

The intended use is like this:

class MyClass
include RM::Mix # defines instance method foo
end

I have another collection of Mixins, which (currently) consists of all
mixins in the previous collection, plus some more:

module IM
include RM
module Max; def baz; puts 777; end; end
end

If I have a class which is supposed to choose from the IM collection:

class MyOtherClass
include IM::Mix # Also defines method foo
include IM::Mux # This defines method bar
include IM::Max # This defines method baz
end

Since I do a include RM within module IM, everything inside RM also goes
into IM.

Now my problem:

I would like to modify the design so that in IM I include from RM only
the mixin Mix, but not Mux. That is, I would like to selectively import
things from another module. I found two solution for this, but I don’t
like neither very much.

Solution 1:

module IM
module Mix
include RM::Mix
end
module Max; def baz; puts 777; end; end
end

Solution 2:

module RM_public
module Mux; def bar; puts 666; end; end
end

module RM
include RM_public
module Mux; def bar; puts 666; end; end
end

module IM
include RM_public
module Max; def baz; puts 777; end; end
end

Question: Is there an easier way in Ruby, which allows me to selectively
include parts from another module?