While When the Camellia Blooms is more of a romantic suspense and Terius Behind me a comedic spy thriller with very little romance, both shows have definitely some similarities. In both dramas:

+ the FL is a single mother
+ the ML gets really attached to the kids
+ the neighborhood plays an important part
+ there is a mystery - a huge conspiracy in TBM and a serial killer in WtCB.

Story of Yanxi Palace is a Chinese and darker version of Dong Yi.

Both dramas follow the same scenario: slave rises in power with her intelligence and wits and earn the love of the Emperor in the process.

Both have scheming consorts, splendid costumes, amazing heroines, sismance and a love triangle.

And both are absolute must watch.