only one body please
no boolleen of boolleen, of boolleen, ....
fixed objects does not mean contraint: the 1st sketch must see all its arcs joined and (better) tangent

we have seen several on this forum
here's one more

It's called "tying your head in knots"

as to move other objects: "Attachment > Placement or Axes"

in this case, make the fillets before making the slots
you will answer me "yes but I was told to do the fillets at the end" you should not always believe what you say
another detail: avoid doing “on surface” sketches because of TNP

this is not exactly what I understand (from the French Wiki) multitransform is possible by using the basic elements
in my example I keep your version of a Polar 2X at 90° and I add a Multitransform of the same hole 3x at 90° to the right
we cannot multitransform a Polar

it's not more complicated to make circles than straight lines, you just need to know where to put the tip of the compass (on LCD screens, it's easier than on old glass screens ), but I'm misplaces, the tool for making arcs by 3 points is very useful

you cannot apply a Multitransform on a PolarPattern (the reverse either)
Multitransform is made precisely to do as many transformations as you want, it still has to be compatible

I see that you are in PartDesign, but you made an Array in Draft, by mixing the 2 workbenchs you created the error

since I'm a good grandpa, I'm going to show you something funny:
you select the upper face (oval) you Pad and at the end you obtain a new perfectly circular section and the same diameter as the base