Creature sizes

I'd like to allow some large and larger creatures to be able to share a portion of their space with certain allied units.
A large creature takes up a 2x2 area. There are many cases where this large creature isn't that much bigger than a medium creature. In this case I'd like the creature to be able to share 2 single tiles with a large or larger ally with a similar build.   For example. A Half-Ogre is large, but an Ogre is also large while the other half of the Half-Ogre is generally a medium sized creature. In this case I'd say a Half-Ogre can share 2 of their tiles with another Half-Ogre. This means that they can be squished together in a 3 tile wide hallway. This also means that an AoE spell with an area of 5feet can hit both targets if it is targeted at the tile where both of them overlap.