Issue... Welding on aluminum adapter brackets

[astroracer]

I had a friend ask about welding affects on the adapter bracket. I need to weld some spacers to the brackets to get the calipers centered over the rotor. The spacers are machined from 6061 T6. Does anyone think this will make the parts unsafe? I know it will affect the heat treat but not sure how badly it will affect it... any advice or thoughts?

I also don't know what the brackets are made of... 6061, 7075... Makes a difference.
I am of the mind that I will just make new brackets out of steel and not worry about it.
Thanks
Mark