SMLLCs are disregarded for federal tax purposes, with that said, heres the rules on when you need a new EIN

When to get a new EIN | Internal Revenue Service

You don’t need a new EIN if you:

• Change your name or locations
• Report income tax as a branch or division of another entity and you don’t have employees or owe excise tax
• Convert a partnership to an LLC classified as a partnership
• Change your tax election to a corporation or S corporation
• Form a single-member LLC and don’t choose to be taxed as a corporation or S corporation and don’t have employees or owe excise tax

Since they have employees, looks like a new EIN is needed.