I don't like this matchup. It basically feels like using a 'wifi Zelda' spamming nothing but Din's Fire and F-smash, which, as mentioned, isn't even that safe. If you're on FD with them then... may Nayru bless your soul. Try to prevent from lagging on any of your moves as much as you can, especially within grab range. If you manage to separate Nana, try and keep her off stage/kill her if possible. She dies stupidly early.
And yes we can down tilt ice blocks, but they have to be well-timed. Her f-smash also blocks ice blocks. Don't ever use Nayru's Love in this MU (not even to block ice blocks) unless you've made some reads on them and you're absolutely certain it will hit. Even then, I wouldn't risk it. Nayru's Love can stop their Blizzard, but I'd still be very wary about bothering with it - better to run away instead and shoot Din's.
Aerial cancels can actually help a lot in spacing/avoiding being grabbed/mixing it up if you know what you're doing. If you're always landing with an air dodge or always in a certain way, they can try to pick up on this and try to punish with a grab. Fighting IC's is more or less like this, depending on how close they are to you:
Far away: Din's fire. Watch out for Ice Blocks, but don't worry about them too much if they hit you a few times. They'll take more damage from Din's then you getting hit by a couple of their blocks, unless you keep messing up the timing.
Mid range: Din's is still viable, but don't charge it for too long. Short ranged Din's can work here, just watch your eyes for the inevitable grab approach.
Kind of close: F-smash. If they try to SSDI and attempt to grab you, immediately follow up with either a spot dodge (risky, but it's better than just leaving yourself open for a grab), or you can try another F-smash or D-smash (also risky, they may expect it and try to shield grab). An alternative option entirely for you is to mix in D-tilt from a reasonable range or run away. If you're cornered, 'aerial run away' by aerial canceling away from them.
Very close: Run away or aerial cancel away. If you absolutely have no option but to attack, your best hope F-smash, D-smash (or even riskier Jab, D-tilt, and Nayru's) will hit and leave you an opening to either follow-up or run away.
Farore's Wind is like a curse on us for this MU, especially if we don't land directly on the ground. I know it's easier said than done, but try to avoid getting knocked off stage/forced to recover as much as you can. Farore's Wind is almost a free grab for them, especially if they know well how the move works.