Metta for dead father During a meditation I have practiced Metta, as I have learned it, I sent Metta to;


myself
a good friend
a "neutral" person
a difficult person
all four of the above equally
and then gradually the entire universe


with the thoughts;


May I be free from enmity/danger
May I be free from mental suffering
May I be free from physical suffering
May I take care of myself happily


Sometime during the meditation I have also sent my Metta to my deceased father. I had a good feeling about it, but wonder whether a Suta this refers?

I want to know whether this form is OK, and how to deal with it.
Generally you should not do Metta to:


Lingavisabhāga (opposite sex - generally directed at a specific person)
Kālakatapuggala (a dead person)


See page 81 Seeing and Knowing revised edition by Pa Auk Sayadaw (Pa Auk Lineage)


  To develop the sublime abiding of loving-kindness (mettà), you need first of all be aware that it should not be developed towards a person of the opposite sex , or a dead person.


Also page 66 Loving Kindness Meditation Ven. Sujiva (Mahaisi Lineage) and page 16 Matta: The Practice of Loving-Kindness As the Foundation for Insight Meditation Practice by Sayadaw U Indaka (Mahasi Sayadaw) also makes the same observation.

In addition Metta: The Philosophy and Practice of Universal Love by Acharya Buddharakkhita (general Theravada) makes the following observation:


  Note that only a living person is to be visualized, not a dead one. The reason for this is that the dead person, having changed form, will be out of the focus of metta-projection. The object of metta always is a living being, and the thought-force will become ineffective if the object is not alive.


Otherwise the what you mention is fine to practice Metta.

Buddhism has the concept of transferring merit to the departed (if they are in a conducive birth to receive it.) This might be something, quite similar, which you can do instead. See: Tiro,kutta Sutta. Also offering to the liberation of ancestors especially your father is highly recommended (one of the "the five uses of wealth" / pañca bhogānam ādiyā) in Patta Kamma Sutta, Ādiya Sutta, Sigāl’ovāda Sutta.

Having said this, this using a deceased person as the subject diminishes the result reaped through Metta meditation. If you find any other physiological benefits by remembering your father, then all means do it, though you will not be getting the benefits expected out of Metta meditation. To get the benefits of Metta meditation focus on all living beings.