You don't mention how the children are related to you. If you don't meet the relationship test, the residency test is irrelevant.
It can't hurt but that is not the documentation the IRS is looking for. Click on the EIC Form 886-H-EIC link below for a list.
The IRS provides a list of documents needed for both dependency and EIC. Normally, if both parents claim a child, the IRS wants proof as listed on the Forms below.
The first item listed is the earned income credit. Your package includes a Form 886-H-EIC that lists all the different documents you can send to prove you may claim the EIC with one or more qualifying children. You can send any combination of these documents to provide the information we need. Look at the Schedule EIC you filed with your tax return and complete the following steps for each qualifying child listed:
The Form 886-H-DEP section for your qualifying child lists all the documents or combination of documents you can use to prove you can claim each child listed as your dependent. To claim a child as a dependent qualifying child, the child must have lived with you for more than half the tax year (the residency test), be related to you (the relationship test), be a certain age (the age test), and not have provided over half of his or her own support (the support test).
For the full topic, please see: https://www.irs.gov/taxtopics/tc654.html