翻訳 - ブラジルのポルトガル語-英語 - "seja feita a vossa vontade"

"thy" is formal or old way of speaking. It's from King James version of the Bible, ancient english, but it fits for "vossa" which is also bible way, at least in brazilian portuguese.

1-Matthew 6.10
10 Thy kingdom come. Thy will be done in earth, as [ it is ] in heaven.

2-Matthew 26.42
42 He went away again the second time, and prayed, saying, O my Father, if this cup may not pass away from me, except I drink it, t .

3-Luke 11.2
2 And he said unto them, When ye pray, say, Our Father which art in heaven, Hallowed be thy name. Thy kingdom come. Thy will be done, as in heaven, so in earth.