Remember, you can check the full document Paschale Solemnitatis on this site, among many on the internet. In these two sections, Rome treats the third major part of the Easter Vigil:
88. The third part of the Vigil is the baptismal liturgy. Christ’s passover and ours is now celebrated. This is given full expression in those churches which have a baptismal font, and more so when the Christian initiation of adults is held, or at least the Baptism of infants. (Cf. The Roman Ritual, Rite of Baptism for Children, 6)
Many parishes–probably most–celebrate the reception of baptized Christians. This can be done, but it is not the first choice. Tradition suggests that baptism is the heart of this portion. Perhaps it could be asserted that Patristic tradition did not know instances of baptized Christians out of union with the local church. RCIA also provides for a combined rite. Whatever a parish decides, it is better that it not be an automatic decision, but one carefully discerned weighing local need as well as the theology of the Vigil.
Even if there are no candidates for Baptism, the blessing of baptismal water should still take place in parish churches. If this blessing does not take place at the baptismal font but in the sanctuary, baptismal water should be carried afterwards to the baptistery there to be kept throughout the whole of paschal time. (Cf. Roman Missal, The Easter Vigil, 48) Where there are neither candidates for Baptism nor any need to bless the font, Baptism should be commemorated by blessing of water destined for sprinkling upon the people. (Cf. Ibidem, 45)
After the baptisms, or at least dealing with the water, the people are questioned.
89. Next follows the renewal of baptismal promises, introduced by some words on the part of the celebrating priest. The faithful reply to the questions put to them, standing and holding lighted candles in their hands. They are then sprinkled with water; in this way the gestures and words recall to them the Baptism they have received. The celebrating priest passes through the main part of the church and sprinkles the people while all sing the antiphon “Vidi aquam” or another suitable song of a baptismal character. (Cf. Ibidem, 47)
Note the instruction that the priest pass through the main part of the church. That probably means that every nook, cranny, cry space, and balcony is not required.
Note the song that accompanies this action should be baptismal in character. Water will likely be mentioned, but it occurs to me that if a song focuses more on the believer’s mission in baptism that will cover the base.