If a donor provides a donation with a request that those funds go to a specific person or family then in general a tax receipt would not be issued.  The CRA provides “However, donations subject to a general direction from a donor that the gift be used in a particular program operated by a charity are acceptable, provided that no benefit accrues to the donor, the directed gift does not benefit any person not dealing at arms’ length with the donor, and decisions regarding utilization of the donation within a program rest with the charity.”  Here is the CRA note on directed donations.

Summary Policy
Date
September 3, 2003
Reference Number
CSP – G05
Key Words
Gift (directed)
Policy Statement
A registered charity cannot issue an official donation receipt if a donor has directed the charity to give the funds to a specified person or family. In reality, such a gift is made to the person or family and not to the charity. However, donations subject to a general direction from a donor that the gift be used in a particular program operated by a charity are acceptable, provided that no benefit accrues to the donor, the directed gift does not benefit any person not dealing at arms’ length with the donor, and decisions regarding utilization of the donation within a program rest with the charity.
References
• Gift, CSP – G01.
• Receipt, CSP – R02.