Hide and Seek by Lynette Eason

Erica James has spent the last three years as a skiptracer, hoping one day it will lead to her kidnapped daughter. Now she has a new suspect--P.I. Max Powell's missing sister. Max has found evidence that connects the two missing girls. Soon the two are drawn together as they search for answers. But the kidnapper will stop at nothing to keep them from finding Erica's daughter...

Secret Agent Father by USA TODAY bestselling author Laura Scott

Although he's never met the boy who arrives on his doorstep, undercover DEA agent Alex McCade can't deny that four-year-old Cody is his child. Shelby Jacobson tells Alex that Cody is the only one who can identify his mother's murderer. So now the killer is after them both. With his newfound family in danger, Alex will do anything to keep Cody--and Shelby--safely by his side.

Previously published as Hide and Seek and Secret Agent Father