As it states in the SFI Affiliate Agreement, transferability of SFI Affiliateship proceeds as follows:

In the event of an Affiliate's death, SFI will keep sending commissions in the method that's been selected on the affiliate's account. For example, if the affiliate had chosen to have his or her commission mailed by check, the affiliate's surviving spouse or other representative must ensure they have the legal right to cash a check made out to the name on the SFI account. However, surviving spouses and representatives can also log onto the affiliate's account and make the necessary adjustments to the account name and information. IMPORTANT: surviving spouses and representatives must have account login information. SFI will not provide that information. Note that, other than this particular exception, logging into any SFI account other than your own is strictly prohibited.