I'd consider mixing Narcissus with Asiatic lilies as they both seem to multiply at similar rates for me.

But not 'mix' as such because I like to lift the Narcissus reasonably regularly to ensure the bulbs in the clump are still at flowering size - and the refresh the soil. The patches stay separate.

The lilies get a bucket of good compost each year to keep them going - plus any supplements I might have to hand. (Mine is seldom an orderly garden...;D) They do better when well-fed, for me.

It may be the varieties I grow - I like to have lilies with cool feet and sunny faces. The spring bulbs often need a good baking to set them up for the following year so only a few patches of Narcissus get near the lilies. I'm easier with clumps of Fritillaria meleagris among them, and F pontica, plus the longer flowering primroses and geraniums.

Perhaps you could consider dedicated patches for the lilies - and disguise the fading leaves with summer annuals and perennials, as well as useful foils such as varying heights of shrubs and grasses.

I have narcissus and lilies mixed at random throughout my beds. All of my beds are mixed trees, shrubs, perennials and bulbs.

I don't need to lift and divide often but if I do, I do it during bloom so I can see where the divisions would look nice with everyone else.