851.41.1. The limited-recourse debt in respect of a gift of a taxpayer, at the time the gift is made, is equal to the aggregate of(a) each limited-recourse amount at that time of the taxpayer and of any other taxpayer not dealing at arm’s length with the taxpayer, that can reasonably be considered to relate to the gift;
(b) each limited-recourse amount at that time, determined under this Title when it is applied to any other taxpayer who deals at arm’s length with and holds, directly or indirectly, an interest in the taxpayer, that can reasonably be considered to relate to the gift; and
(c) each amount that is the unpaid amount at that time of any other indebtedness, of any taxpayer referred to in paragraph a or b, that can reasonably be considered to relate to the gift if there is a guarantee, security or similar covenant in respect of that or any other indebtedness.