Connective words like "to", "and", "the" and "of" are never included in the acronym unless they're needed to form a pronounceable word.
Even then they're not capitalized, in a rule similar to movie titles, like "Monty Python and the Holy Grail", or "Don't Be a Menace to South Central While Drinking Your Juice in the Hood".
So if the "to" were to be included in the acronym and you wanted to truly be OCD about it, it wouldn't be "MILTF", it would be "MILtF". ;-P lol