The Empress Consort was the principal wife, and in theory the oldest son of the first Empress Consort had priority on becoming the Crown Prince, even if lower-status wives had sons who were older, but in practice this hinged on how good the Empress Consort and her birth-family played the game of palace politics. (Whether the Crown Prince actually succeeded his father was a whole other kettle of wax.)
There were multiple ranks of consorts and wives and concubines, resulting in a large harem quarter, but in practice the lowest levels of concubines never even saw the Emperor but were attached to his household in order to give them access to the harem as higher-level servants to the other consorts and higher-level concubines.
So, if your older son was from a secondary consort and the younger from the Empress, then yes, that's an entirely plausible scenario, without bothering with the convoluted (and deeply politics-filled) divorce scenario. The divorce and remarry thing couldn't/wouldn't happen, actually.
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The Empress Consort was the principal wife, and in theory the oldest son of the first Empress Consort had priority on becoming the Crown Prince, even if lower-status wives had sons who were older, but in practice this hinged on how good the Empress Consort and her birth-family played the game of palace politics. (Whether the Crown Prince actually succeeded his father was a whole other kettle of wax.)
There were multiple ranks of consorts and wives and concubines, resulting in a large harem quarter, but in practice the lowest levels of concubines never even saw the Emperor but were attached to his household in order to give them access to the harem as higher-level servants to the other consorts and higher-level concubines.
So, if your older son was from a secondary consort and the younger from the Empress, then yes, that's an entirely plausible scenario, without bothering with the convoluted (and deeply politics-filled) divorce scenario. The divorce and remarry thing couldn't/wouldn't happen, actually.