Couple of questions for you...
Are they eating? Are they drinking? How does their poo look now? Foamy? Yellow? Green? And blood? Do they have access to a heat source? When you feel their crops, how much food and/or water is in there (crop is at base of neck on right side)?
About the Safeguard... If it is coccidiosis, waiting a few days won't hurt. If it's histomoniasis, I wouldn't wait. As for mixing Corid and Safeguard in the same waterer, I don't know if people do that. If you do, then they might not drink enough, if any, and get sicker. Maybe someone could comment on the pros and cons of doing so?
This is just a reference for you... I have two others that hatched 7/23 and 7/25 and they weigh, as of today, 999 grams and 866 grams. My smallest two hatched 8/4 and 8/21 and they weigh 607 grams and 345 grams.
This is how much Safeguard I gave mine today:
1325 grams = .66cc
1265 grams = .63cc
999 grams = .5cc
866 grams = .43cc
607 grams = .3cc
345 grams = .17cc
Your two would get:
581 grams = ~.28cc
357 grams = ~.18cc
But the above is only if you feel like you could hold them still enough to place the syringe down the oesophagus. Otherwise, they might aspirate (breath in) the wormer.
http://www.daff.qld.gov.au/27_2705.htm
Do you have a 1cc sryinge? Anything larger is too wide to do most birds safely. Also, wipe off excess liquid before inserting syringe. Please do not attempt to drip it into their mouths as they can aspirate this way, too.
Any word on the metronidazole?
-Kathy