XY Graphs are specifically documented to open a different window for each block, and only permit scalar X and scalar Y. But you can see the File Exchange https://www.mathworks.com/matlabcentral/fileexchange/75379-multiple-xy-graph?s_tid=srchtitle_xygraph_4
If you do not need rapid acceleration, then you can use MATLAB Function Block and coder.extrinsic() the names of the graphics routines.
For setting a block parameter from MATLAB you can set_param(). But see https://www.mathworks.com/matlabcentral/answers/1653710-global-variable-in-simulink#comment_2009495 for how to create global variables that Simulink can use.