Spies and Thieves Recommended Reading Order

I'd Tell You I Love You, but Then I'd Have to Kill You (Gallagher Girls #1)
Cross My Heart and Hope to Spy (Gallagher Girls #2)
Don't Judge a Girl by Her Cover (Gallagher Girls #3)
Only the Good Spy Young (Gallagher Girls #4)
Out of Sight, Out of Time (Gallagher Girls #5)
United We Spy (Gallagher Girls #6)
Classified Files (Gallagher Girls #4.5)
A Gallagher Wedding (Gallagher Girls #6.5)
Heist Society (Heist Society #1)
Uncommon Criminals (Heist Society #2)
Perfect Scoundrels (Heist Society #3)
Double Crossed (Gallagher Girls #5.5; Heist Society #2.5)
The Gift of the Magi (Heist Society #3.5)