RIFTS REPORTED IN BONN COALITION
deadline for nominating W Ger presidential candidate, set for May 10, is postponed to May 14 at request of Free Dem party; postponement brings rumor that Free Dem candidate Foreign Min Walter Scheel may not run in May 15 election; his election to presidency had been considered foregone conclusion; Free Dem spokesman calls postponement technical one; Socialist leader Herbert Wehner warns that if Socialists fail to vote for Scheel, Free Dems might refuse to endorse Helmut Schmidt; action behind maneuvering is intense resentment many Socialists feel for Interior Min Hans-Dietrich Genscher, who is slated to replace Scheel; 2 Opposition Christian Dem leaders seek formal investigation of case of Susanne Sievers, former intelligence worker who is said to have been paid $160,000 by W Ger intelligence not to publish book about her alleged liaison with Willy Brandt; case revd (M)