Wash and slice the kumquats and oranges into thin strips, making sure to remove the seeds.
Weigh them and put them in a large pot with 3 times their weight in water.
Let it sit for 12 hours.

The next day, bring the mixture to a boil, then cook over low heat, uncovered, until the fruit is tender, about 40 minutes.

Weigh the entire mixture (water + fruit) and add their weight in sugar to the pot with the lemon juice.

Cook until the mixture reaches 220 F (104 C) on a candy thermometer.
Add the milk jam, mix, and give it a final boil.
Pour into sterilized jars and put on the lids.