(a) Instruments executed prior to September first, nineteen hundred ninety-two. Whenever a disposition of property is made to "issue", such issue, if in equal degree of consanguinity to their common ancestor, take per capita, but if in unequal degree, per stirpes, unless a contrary intention is expressed.
(b) Instruments executed on or after September first, nineteen hundred ninety-two. Whenever a disposition of property is made to "issue", such issue take by representation as defined in 1-2.16, unless a contrary intention is expressed.