"A preliminary transaction will form part of the series of transactions or events determined with reference to subsection 248(10) if, at the time that the preliminary transaction is carried out, the taxpayer is intending to implement the subsequent transactions constituting the series, and the subsequent transactions are eventually carried out. Thus, the preliminary and subsequent transactions will be part of the series even though at the time of completing the preliminary transactions the taxpayer either had not determined all the important elements of the subsequent transactions - such as, for instance, the identity of the other taxpayers involved - or lacked the ability to implement the subsequent transactions."