The Registrar can include as part of your ceremony a thank you to those who have traveled from away for attending or someone who has helped with the all the arrangements. . If some family members or friends are unable to attend the ceremony they may wish to write a letter or poem that can then be read out during the ceremony.
[Party 1] and [Party 2] would like me to make a special thank you to [guests name] and [guests name] who have travelled from [place/city] to be here today, it has been very much appreciated.
[Party 1] and [Party 2] would like me to make a special thank you to [guests name] who without their help today would not have been made into such a memorable day.