Boundary condition for finite element problem

In finite element, I have a cantilever beam (system level) consisting of components A and B joined together (as shown in the figure below). I applied a force of 1N at the free end of the cantilever and I got the x- and y-displacement of each node. Now, I want to isolate component A (component level) and apply boundary conditions to it. My goal is to achieve similar x- and y displacement on each of the nodes of component A, both at the system level and component level. How can I go about it? What boundary condition(s) can I apply to component A only in order to achieve the similar nodal displacements I had when components A and B are combined? I also need a MATLAB code for the implementation.

Thank you.