Order indicators in the .xsd file

Hi XML experts,

I have a problem about the use of order indicators in the creation of
XML schema (.xsd file). As I learned from W3School
(http://www.w3schools.com/schema/schema_complex_indicators.asp),  we
have 3 order indicators in the XML Schema language:

All - the child elements can appear in any order, and each child
element must occur only once
Choice - either one child element or another can occur
Sequence - the child elements must appear in a specific order

I have an element (for example <asset>) that has 23 child elements,
three of them can have more than 1 instances, and 7 of them are
required (includes the 3 have more than 1 instances). According to the
definition of the order indicators, "sequence" is the only indicator I
can use in the XML schema, but I hope there is no order restriction
for the appearance of  23 child elements. Do you have any ideas to
solve this problem?

Thank you,

Fred Li