For full context: http://www3.nhk.or.jp/news/easy/k10011281951000/k10011281951000.html
The sentence in question:
My attempt at translation:
"Concerning the Bunkyo Civic center, considering to get the foreigners to come to come-of-age ceremony, where one gives gifts to the new adults, one sent letters which one has written in friendly english and japanese."
First, I hope I translated the intentional form もらおう here correctly. Im also not sure wether I interpreted the second meaning for もらう correctly here http://jisho.org/search/morau.
My main issue here is 成人式に外国人に. I think 成人式に expresses a direction here in relation to the verb 出る for which I used the meaning "to come to". 外国人に is a bit harder for me, since
A) I'm not sure what particle もらう demands when it has the meaning "to get someone to do something".
B) I am always a bit confused when a complex block of verbal expressions basically acts on two nouns. Syntactically, I think 外国人 must be the object of the predicative 出てもらおうと考えて, and would probably be categorized as an adverbial with local information. But I'm not sure, since I think that the verb 出る in the meaning "to come to" definitely requires an object, which would be 成人式. If thats true then the verbal expression 成人式に出る would be nested into the verbal expression 外国人にもらおうと考えて which itself required a verb (here 出る) to have the meaning "to get someone to do something". All these relations really make me skeptic of my interpretation, since I dont really know how to understand whats going on and therefore I cant be sure that I got it right ^^