Grammatically conditioned allomorphy, paradigmatic structure, and the Ancestry Constraint

When inflectional allomorphy is grammatically conditioned, are there any constraints on the direction of conditioning (inward or outward)? Claims made by Bobaljik (2000) and Carstairs (1987) are compared with respect to data from Hungarian, Itelmen and Latin. An answer is suggested that exploits the notion of direct ancestry (relationships between (grand)mothers and (grand‐)daughters) in word‐structure trees, and the notion of blur avoidance in paradigmatic structure (Carstairs‐McCarthy 1994). Implications for Stump's (2001) theory of paradigm structure are briefly discussed.