This is how Thomas and Lady got married in Thomas and Lady's New Son.
Percy: I can't believe you and Lady are getting married, Thomas, I'm so happy for you!
Thomas: Thank you, Percy!
Lady: How do I look?
Rainbow Dash: You look ready for the wedding, Lady!
Later, Friar Tuck was ready to perform the wedding.
Friar Tuck: Dearly Beloved, We are all gathered here today in sight of the lord thy god to bear witness to the union of Prince Thomas and Lady. Do you Prince Thomas take Lady as your lawfully wedded Wife to have and to hold in sickness and in health for as long as you life until death?
Thomas: I do.
Friar Tuck: And do you Lady take Prince Thomas as your lawfully wedded Husband to have and to hold in sickness and in health for as long as you life until death?
Lady: I do.
Friar Tuck: Now that the vows are made, Luke, Do you have the rings?
Luke: Yes, Friar Tuck, I have the rings!
Friar Tuck: I now pronounce you Stallion and Mare, You may kiss the bride!
Thomas and Lady: (kissed)
Discord: (sheds a tear) That is so wonderful! (blows a tissue)
Princess Celestia: I'm really happy for them, Topham.
Sir Topham Hatt: So am I, Princess Celestia and under any circumstances, Thomas and Lady will always be engines at heart, Especially Hiro.
After the wedding, Thomas and Lady left on their Honeymoon.
Thomas: Are you ready, Lady?
Lady: Then you are, Thomas.
Skarloey: Goodbye, Thomas! Goodbye, Lady!
Thomas: Goodbye, Everyone! Goodbye, Everypony!
Percy: Goodbye, Thomas.
James: See you real soon!
Gator: God Speed, Prince Thomas and Princess Lady!
Percy: I hope they'll have a great time, Gator.
Gator: Me too, Percy, Me too!