[CAUT] breaking strings

[Karen Lindsley]

I have a customer with a Doll and Sons small grand piano.  It was
recently restrung using the original string gauges and pattern.  The
upper treble is very sensitive to tuning and strings have broken
during two of the last four tunings at intervals of six months.  I
went to tune it again and another string had broken since my last
tuning.  Any ideas?  Can I change the string size and get more
elasticity out of the strings?
Thanks for your input.
Karen