How can people meet again after rebirth? Prince Siddhartha &amp; Princess Yashodhara met in a lot of lives as partners. How are people intended to meet their present life relations in the next life? Is the desire needed to be wished upon?
If you both have:

(1) compatible faith (sama,saddhā),
(2) compatible virtue (sama,silā),
(3) compatible charity (sama,cāgā),
(4) compatible wisdom (sama,pannā).

Sama,jivi Sutta 1
With the balance of probability, you will be born in the same plane, which increases the chance of meeting again. There is no guarantee through. This will make your current life together effective.
What is desirable is not achieved through wishing or praying, but through action resulting is conducive karma, i.e, convergent, action-based karma from both parties should spontaneously effect reunion:

they are not to be obtained through prayer (ayacana,hetu) or through wishing (patthana,hetu)

Pañcaka Iṭṭha Sutta

all of them are rooted in diligence, converge on diligence,

(Hatthi) Pada Sutta