Okay, I'm always a little confused about this. Here's the sentence: "She grabbed the bill and picked Moriah up." Here's my question, should I put "up" before or after "Moriah," what's the rule? They both sound acceptable to me.
You can usually do it either way. See which way sounds the way you want it to. With those types of constructions, the restriction comes into play when a pronoun is the direct object. In that case, usually the pronoun has to be right after the verb (though there can be exceptions, such as when the pronoun is intentionally being "stressed"). E.g. 1a. Mark picked him up. 1b. NOT: *Mark picked up him. Sometimes a writer will consider the weight of the direct object; and if it is relatively heavy, then maybe postpose that direct object (as in #2b below). The direct object is underlined. E.g. 2a. Mark picked the soggy twelve-hundred-year-old family heirloom up. 2b. Mark picked up the soggy twelve-hundred-year-old family heirloom. Otherwise, the writer can probably choose either way. What the writer might use to affect his decision could be the context, as to what the surrounding sentences sound like, and how those sentences transition to and from your "problem sentence". ASIDE: Some grammars call that word "up" in that type of construction as a "particle". And they might make the comment that particles are the only complements that can be inserted between a verb and its direct object; for otherwise, usually, the direct object is right after the verb (except for maybe those times when an adjunct is between them).
in your sentence, the 'up' dangles awkwardly, so putting it before the name reads much more smoothly... that said, if you added 'from the floor' [were the child sitting/standing/lying there], 'up' would necessarily have to be placed after it...
Some prescriptive grammars say that prepositions mustn't go at the end of a sentence. Although "up" in your sentence isn't actually functioning as a preposition (it's functioning as part of an idiomatic phrasal verb) it still feels a little uncomfortable, possibly because it subconsciously triggers the rule anyway. I think that's where Mamma's "dangles awkwardly" comes in. It's better not to put it at the end of the sentence unless there's an overriding reason to do so, such as the example F.E. gave.