The correct words for the blanks are:
(1) They're
(2) there
The correct sentence would be: "They're three company managers who submitted the committee proposals to there."
Step-by-step explanation:
"They're" is a contraction of "they are," and it is used to refer to the three company managers who submitted the committee proposals.
"There" is an adverb that indicates a place, and it is used to refer to the location where the committee proposals were submitted.