Permission to ordain from absent father
I would speak to the preceptor you wish to ordain with. 


  There is no need to get a parent’s permission if he/she is no longer
  alive or has abandoned the son. From this it can be argued that if the
  parents are divorced and one of them has totally abandoned
  responsibility for the son, there is no need to get permission from
  that parent. If, however, both parents continued to assume
  responsibility for the son, he needs to get the permission of both.
  
  https://www.dhammatalks.org/vinaya/bmc/Section0054.html