When ending Y is not part of a vowel team and changes to I before suffix -ED, it usually keeps the same sound as it forms ending -IED, and the combined ending becomes /ēd/  as in “muddy” to “muddied”.

Ending /ēd/, Ending /ēd/, Ending /ēd/, muddied

When ending Y is followed by Suffix -ED, you may circle the resulting combined Ending -IED. You also have the option of writing the Y below the I that resulted from the Change Suffix Ending function.