After removing our tub & tile to install a new one, we discovered rot in the floor and along a section of the bottom plate. However it appears that directly above the rotted part is the end of a trust with a doubled up 2x4's going from the bottom of the trust to the rotten bottom plate. How do I go about replacing this bottom plate since this is apparently load bearing. the rot is right under the doubled up 2 x 4's.

this is what it looks like since it won't let me upload a picture.

[ || ] Trust
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|||| doubled up 2 x 4's
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_______________________________ Bottom Plate