Two or more future estates may be created to take effect in the alternative, so that if the first in order shall fail to vest the next in succession may be substituted for it and take effect accordingly.
D.C. Code § 42-513
Future estates — Alternative
Mar. 3, 1901, 31 Stat. 1352, ch. 854, § 1026
Official source: D.C. Law Library (Council of the District of Columbia). Reproduced from public-domain District of Columbia statutes; confirm against the official source for the current text. Not legal advice.