Applcation.Volatile = True

Sub Master()
If Macro1 = false then Exit Sub 'тоже самое с остальными
Call 2
Call 3
Call 4
End Sub

Function Macro1()
    Dim c As Range
    For Each c In Selection
        If IsError(c.Value2) Then c.Select: MsgBox "Err", 16, "": Exit Function
    Next c
    MsgBox "OK", 64, ""
    Macro1 = true
End Function

Public IsErr as boolean
IsErr = False
Sub Master()
Call Macro1
If IsErr = True then Exit Sub 'тоже самое с остальными
Call 2
Call 3
Call 4
End Sub

Sub Macro1()
    Dim c As Range
    For Each c In Selection
        If IsError(c.Value2) Then c.Select: MsgBox "Err", 16, "": IsErr = True: Exit Sub
    Next c
    MsgBox "OK", 64, ""
    Macro1 = true
End Sub

Sub Macro1()
    Dim c As Range
    For Each c In Selection
        If IsError(c.Value2) Then c.Select: MsgBox "Err", 16, "": End
    Next c
    MsgBox "OK", 64, ""
    Macro1 = true
End Sub

Sub BtcBid()
    Dim pair
    pair= "то, что передавалось в функцию этим параметром"
    Dim xmlhttp As New MSXML2.XMLHTTP60, myurl As String
    Dim x As Object
 
    API = "https://btc-trade.com.ua/api/ticker/" + pair
    xmlhttp.Open "GET", API, False
    xmlhttp.Send
    Set x = ParseJson(xmlhttp.responseText)
    Set xmlhttp = Nothing
     
    MsgBox val(x(pair)("buy"))
End Sub