Again, thinking non-metrically, a quart is ~ .947 liter (volume) so a bit more ether will be needed to bring a liter of blend over 10% to 12% ether. (A liter fits into a quart can, and I use a 1000cc graduate to simplify mixing a batch. Desired percentages then measure directly in cc...)
I think you mean that a US Quart will fit into a Litre can.
One US Quart = 0.946353 Litres
One Imperial Quart = 1.13652 Litres
If you're concerned about accuracy then it's not a good idea to use a 1000 ml Graduated Cylinder to mix fuel.
Let's say the mix is 20:30:50 known almost universally as "Olly brew".
One procedure is usually to pour (say) 200 ml of oil, then add enough Ether to the 500 ml mark, and then top it up with Kerocene.
I suspect that this is what you're suggesting.
As soon as you pour the Ether in some of the oil will dissolve in it. So you're actually adding more Ether than the recipe requires.
Same with the Kero but probably to a lesser extent.
The accepted routine is this if you're shooting for a 20:30:50 ratio:
Use the Graduated Cylinder to measure each individual component in turn. It's best to measure and pour the Ether or Kero first. Once you're measured pour each into a mixing bottle. If you shake up the latter and pour it back into the Cylinder you'll find you've "lost" about 30 ml. This is normal.