x1 is a grandparent of x2 by bond/tie/relation/standard x3 (not necessarily genetic/biological nor necessarily directly ancestral); x1 is an associated member of x2's parent(s)'s parent(s)'s generation.
x1 and x2 are mutual sibling nodes in a directed tree graph x6 such that their shared parent node(s) x5 is/are the most-recent common direct ancestor of x3 and x4, such that x1 is a direct ancestor of or simply is x3 (as the case may be), and such that x2 is a direct ancestor of or simply is x4 (as the case may be), all according to tree ordering relation x7.
x1 (node in a tree graph) and x2 (node in the same tree graph) have an essentially unique most recent (graph-nearest) common ancestor node A such that x3 [nonnegative integer; li] is the minimum element of the set consisting only of d(A, x1) and of d(A, x2), and such that x4 [integer; li] is d(A, x1) - d(A, x2), where d is the graph geodesic distance (defined to be infinite if nodes are not connected in the correct direction).
x1 is analogous to a sibling in a rank/seniority for/of a rirny'utka of x2 by standard/in hierarchy/via partial ordering or relation(ship) x3 (this is the connection between the rirny'utka at hand and x1 which justifies the treicytunba label), where x2 and the said rirny'utka are connected via intermediate steps x4 (ce'o).