How to run keyword tests which are in another project (of the same project suite)

Is there a possibiti/good approach to achieve following:



Project suite X

contains projects a and b

project a contains keyword test a1

project b contains keyword test b1



In keyword test a1 I want to invoke keywordtest b1, however when I use the command Run keyword test from within a1 I can only select other tests from within project a



Please explain what would be the best approach to use this scenario?