public class Config {
    static Dictionary<int, IHandler handler> dictionary = new Dictionary<int, IHandler>() {
        { 0, new Handler() },
        { 1, new Handler() },
        { 2, new SecondHandler() }
    };

    public static IHandler Get(int id) { return dictionary[id].handler; }
}

interface IHandler {
    void Execute(SqlConnection sqlConnection, SqlTransaction transaction, List data);
}

class Handler : IHandler {
    public void Execute(SqlConnection sqlConnection, SqlTransaction transaction, List data) {
        ...
    }
}

interface IHandlerSecond {
    void Execute(SqlConnection sqlConnection, IConnection connection, SqlTransaction transaction, List data);
}

class SecondHandler : Handler, IHandlerSecond {
    public void Execute(SqlConnection sqlConnection, IConnection connection, SqlTransaction transaction, List data) {
        base.Execute(sqlConnection, connection, transaction);
        ...
    }
}

void Main(IConnect connect) {
    // Some code

    var handler = Config.Get(num);
    if(handler is IHandlerSecond) {
        (handler as IHandlerSecond).Execute(connect, iconnection, transaction, data);
    } 
    else if (handler is IHandler) {
        (handler as IHandler).Execute(connect, transaction, data);
    }
}

So base signature looks like

    void Execute(SqlConnection sqlConnection, SqlTransaction transaction, List data);

but one handler accepts one more parameter and I trying to find best way to do this.

My best idea was to just make another interface and check for type in main function, but it’s looks kinda messy