The new combined feast comes with a new prayer!
When Pope Francis decreed that July 29 be the memorial of Sts. Martha, Mary and Lazarus, he also authorized the formation of new liturgical texts.
This means that the opening prayer for today now reflects all three siblings, asking them for heavenly intercession.
Below is an interim translation of the Latin that will be used this year.
Grant, we pray, almighty God,
that the example of your Saints may spur us on to a better life,
so that we, who celebrate the memory of Saints Martha,
Mary and Lazarus,
may also imitate without ceasing their deeds.
Through our Lord Jesus Christ, your Son,
who lives and reigns with you in the unity of the Holy Spirit,
God, for ever and ever.
Or you can use the official Latin text.
Deus, cuius Fílius
de sepúlcro ad vitam Lázarum revocávit,
et in domo Marthæ dignátus est hospitári,
da nobis, quǽsumus,
ut ipsi in frátribus nostris fidéliter ministrántes,
cum María verbi eius meditatióne pasci mereámur.