'Holding' rewards flights

Hi All,
I am sure I should know this, but.......
I am looking at flights for next summer to MCO for 3 pax and I have a couple of Amex upgrade vouchers.
With the 330 (?) day rule there are seats released for the outbound, but not the return.
Does anyone know how I can bag the outbound until the returns are released?
I am looking for potentially 3 weeks so that is a very long time for those outbound seats to remain available unless I can hook them somehow.
Thanks
I am sure I should know this, but.......
I am looking at flights for next summer to MCO for 3 pax and I have a couple of Amex upgrade vouchers.
With the 330 (?) day rule there are seats released for the outbound, but not the return.
Does anyone know how I can bag the outbound until the returns are released?
I am looking for potentially 3 weeks so that is a very long time for those outbound seats to remain available unless I can hook them somehow.
Thanks