अणुभाष्य (महाप्रभु वल्लभाचार्य - शुद्धाद्वैत वेदान्त ब्रह्मसूत्र महाभाष्य प्रकाश टीका सहित)

ād bhagavan...
Yes! तादात्म्यात् becomes तादात्म्याद् before bh!
Then भगवत्-निष्ठा becomes भगवन्-निष्ठा (t + n = nn)!
So: तादात्म्याद् + भगवन्निष्ठा = तादात्म्याद्भगवन्निष्ठा!
Wait, why would it be "भगवद्विष्ठा..."?
If it were bhagavat + viṣṭhā, that makes no sense in Vedanta!
"भगवन्निष्ठा" makes 100% sense! "भगवन्-निष्ठा" = devotion/steadfastness in Bhagavan!
Wait, let's look at the letter between व and ष्ठा:
It has a curve on top: that's an 'i' matra!
And underneath, it's NOT 'द्वि', it's 'न्नि' (double n)!
Yes! 'न्' + 'नि' = 'न्नि'!
So it is definitely:
भगवन्निष्ठा (bhagavanniṣṭhā)!
Now, what is after भगवन्निष्ठा?
Let's look at the next characters:
There is:
'सृ' (or 'स्मृ' or 'मृ' or 'श्रु')?
Wait! Could it be:
"भगवन्निष्ठावताम्"?
Look at the characters:
Is there a 'व'?
Look: after ष्ठा, there is:
A character with a bottom