I have a similar question to Why is it a sheva na in ha-leviyim?
I have seen some siddurim indicate a shva nach in the yud of שֶׁכֵּן חובַת כָּל הַיְצוּרִים (shacharis of Shabbos, before yishtabach). And some a shva na.
Same thing for וְגַם כָּל הַיְצוּר לֹא נִכְחַד מִמֶּךָּ and כִּי זֵכֶר כָּל הַיְצוּר לְפָנֶיךָ בָּא (musaf of Rosh Hashana, bracha of zichronos).
As can be gathered from the answers to the above referenced question (and other questions on this site) the shva following הַ (meaning "the"), when the following letter does not have a dagesh, should be shva na only when the הַ has a meteg according the biblical mesorah. However, in this case, I have not found that word in tanach, so there would be no way of verifying that rule for this word.
My question is not which way is correct, but rather what consideration would the siddur editor take for such a word that is not found in tanach, and why would some editors conclude it's nach and some na?
