(upon divorce ex-husband agreed to pay for ex-wife's interest in family farm; ex-husband later sought to renew line of credit and restructure farm's debt to pay ex-wife and bank required ex-wife's agreement to give bank lien priority over ex-wife's; upon ex-wife's refusal trial court granted ex-husband's declaratory order subordinating ex-wife's lien; upon review, court reverses - parties' settlement agreement did not address issue but only contemplated only regular annual renewal of farm's debt to finance farming operations, but not higher level of debt necessary to finance ex-husband's obligations to ex-wife).