♪♫ Hallel at Maariv ♫♪
The general minhag in Eretz Yisrael is to say Hallel Shaleim with a berachah on the first night of Pesach in Shul, b’rov ahm.
It is an exalted time. Yet the urge to sing and praise HaShem slowly and deliberately MUST be balanced against Chazal’s insistence that we do not delay at all the seder of the night, so as to maximize engaging the whole family (and oneself) in the mitzvohs of the evening, and their full meaning and import.
♪♫ Hallel During the Seder ♫♪
Tur writes: Finish Halel, say that last berachah (yehalleluchah) up until the baruch atta at the end; then say hallel hagadol (26 ki l’olom…) and then nishmas, say yishtabach, but conclude yishtabach (after may’atta v’ad olom) with Baruch atta…melech mehullal batishbachos.
The Levush says: No, conclude yishtabach as one normally does.
The Beis Yosef indeed asks on the Tur-why not conclude yishtabach in the normal way? Beis Yosef suggests: Finish Hallel; do NOT say yehalleluchoh; then say Hallel hagadol, nishmas, and yishtabach up until its concluding berachah (until you say may’atta v’ad olom); then say yehaleluchoh and conclude melech mehullal batishbachos.
And so he paskens in Shulchan Aruch.
Aruch haShulchan says: That is what our minhag is
Pri MeGedaim says: do either like the Shulchan Aruch or the Tur, but certainly concluding with melech mehullal batishbachos.
Mishneh Berurah is not machri’a. (see Shaar Tziyun 480:5)
Good luck! and whatever you do, don’t say the berachah twice or make BOTH berachos!