Can’t see your blend or what you are trying to accomplish. All you told us is you set up an IK TO FK switch following some tutorial. Are you going from IK to FK? FK to IK? How many bone chains do you have? What is the animation? Can you blend your switch with the rig you used? If you can’t you need another rig. If you don’t know put a blend in so I or someone else can help you. Here is some help on rigging and animation.
Rig your arm this way https://www.youtube.com/watch?v=6ECcLg-S_Is
Then blend your FK to IK movement like this Seamless IK/FK blending 2.5
Or if you’re into significant scripting you can copy matrix positions from one bone chain to another. (If you don’t know what a matrix position is, forget this for now and as you gain more experience, look at the IK to FK snapping script in rigify and adapt it or try this script IK/FK snap / switch - how?).
Remember, we can’t see what you are doing in the animation so we don’t know what “snapping to both keyframes” means. Once you put a blend in, then you can explain what you want to happen and then maybe we can help you.